Chirality transfer across length scales is an intriguing and universal phenomenon. Both in nature and in materials science, complex architectures composed of bio-based chiral building blocks are responsible for unique optical responses from bright and vivid colourations to extremely large dichroism. When it comes to working with naturally derived chiral building blocks, however, the challenge lies in understanding how the properties of individual building blocks relate to the emergent features of large-scale architectures and structures. Our research addresses this gap by investigating the origins of mesophase chirality in bio-derived particles such as cellulose and chitin nanocrystal suspensions. Through a combination of quantitative morphological analysis of individual nanoparticles, final architecture, and their assemblies, we showcase the functionality of such chiral materials in the context of optical materials, including plasmonic ones, also providing examples of how such materials can be produced at scale.

Scalable quantum photonics demands advanced, multi-targeted optimization of emitters, resonators, couplers, waveguides and other elements of on-chip circuitry, as well as control elements under realistic conditions such as noise and fabrication constraints. Machine learning (ML) provides a unifying framework both for navigating high-dimensional photonic design spaces and for speeding up quantum measurements as well as for forecasting the temporal dynamics of quantum emitters’ behavior that is critical for coherence control. In silicon nitride (SiN)–compatible photonic integrated circuits, generative and surrogate-based inverse design enables rapid co-optimization of waveguides, resonators, and emitter–circuit interfaces, supporting multiplexed architectures and manufacturable layouts. ML also enables anticipatory mitigation of decoherence: models trained on sparse spectral measurements can predict spectral diffusion and dephasing trajectories of solid-state emitters, allowing feed-forward stabilization and improved photon indistinguishability across devices. Complementing these ML-enabled capabilities, adjoint topology optimization of couplers between hexagonal boron nitride (hBN) room-temperature single-photon sources and SiN waveguides enables fabrication-aware, position-robust interfaces that mitigate modal mismatch and achieve high simulated coupling efficiencies. Together, decoherence-aware ML design and prediction, SiN-integrated emitters and circuitry, and robust emitter–waveguide coupling define a viable path toward stable, scalable quantum photonic systems.

This talk demonstrates recent advances in meta-optics inverse design, emphasizing a Nyquist-sampled time-domain adjoint framework that drastically reduces FDTD memory while preserving gradient accuracy for broadband metalens optimization. It also introduces physics-guided diffusion models as a scalable, fabrication-aware nanophotonic design method.

We present our advances on the model- and data-driven inverse design of photonic materials described within a scattering framework. The model-driven approach is based on an automatic differentiation of a code for the forward problem. The data-driven approach leverages a newly established data repository for T-matrices to train neural networks.

Put your abstract hereIs it feasible to alter the ground state properties of a material by engineering its electromagnetic environment? Inspired by theoretical predictions, including works by many speakers of this exciting workshop, experimental realizations of such cavity-controlled properties without optical excitation are beginning to emerge. Our team devised and implemented a novel platform to realize cavity-altered materials. Single crystals of hyperbolic van der Waals (vdW) compounds provide a resonant electromagnetic environment with enhanced density of photonic states and prominent mode confinement. We inter-faced hexagonal boron nitride (hBN) with the molecular superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br (κ-ET). The frequencies of infrared (IR) hyperbolic modes of hBN match the IR-active carbon-carbon stretching molecular resonance of κ-ET im-plicated in superconductivity. Meissner effect measurements via magnetic force microscopy demonstrate a strong suppression of superfluid density near the hBN/κ-ET interface. Our work highlights the potential of dark cavities devoid of external photons for engineering electronic ground state properties of complex quantum materials. I.Keren, T.Webb et al. Nature Nature 650, 864 (2026).

In this talk, I will present our recent progress in developing a theoretical framework for predicting nonlinear susceptibilities in superconducting meta-atoms and metamaterials.

Low-symmetry two-dimensional materials exhibiting Berry curvature dipoles can generate terahertz optical gain under DC bias. We introduce a compact cavity platform that enhances light–matter interactions, enabling bias-controlled, chiral, and polarization-selective terahertz amplification and lasing driven by non-Hermitian electro-optic effects.

We demonstrate that isotropic, experimentally accessible Kramers qubits coupled to structured plasmonic environments can exhibit spin ordering rooted in spontaneous time-reversal symmetry breaking, previously linked to qubit anisotropy. A nonlinear Bloch equation governs the spin dynamics, enabling time-crystal states and mono- or bistable configurations. Higher-order multistability is topologically forbidden.

Plasma discharges offer a unique opportunity to implement reconfigurable metastructures at microwave frequencies. Unlike conventional solid-state tuning approaches, plasma behaves as a dispersive electromagnetic material whose constitutive parameters can be continuously controlled through electrical excitation. In this contribution, we examine plasma as a competitive platform for reconfigurable metastructures and establish a unified framework for their design. We summarize key theoretical and experimental results obtained in our recent investigations, including analytical modeling of canonical plasma inclusions and electromagnetic retrieval of non-uniform plasma parameters. Their implications for the design of plasma-based metasurfaces and metagratings integrated with antenna systems are outlined. The presented framework supports the view of plasma as a viable and physically robust building block for adaptive radiating structures.

We investigate large-area α-MoO₃/VO₂ heterostructures as dynamically tunable platforms for mid-infrared (8–20 μm) photonics. The synergistic coupling between anisotropic α-MoO₃ and phase-change VO₂ enables dynamic control of mid-IR spectral features, providing a scalable route toward reconfigurable infrared photonic devices for thermal radiation management and adaptive metasurfaces.

Thermally tunable, free-standing silicon metasurfaces that support high-Q bound states in the continuum enable dynamically reconfigurable mid-infrared spectroscopy in transmission mode. Continuous resonance tuning enhances molecular fingerprint detection and facilitates vibrational strong coupling, providing a scalable platform for compact biochemical sensors and actively programmable light–matter interactions.

By exploiting strong light-matter coupling in chiral 2D perovskites, we demonstrate room-temperature, continuous-wave circularly polarized lasing across visible and infrared spectra.

Achieving efficient second-harmonic generation in compact lithium niobate metastructures remains challenging due to the limited mode overlap and weak field confinement in subwavelength geometries. Here we present a viable design strategy for LN metastructures that enables robust and efficient second-harmonic generation (SHG). The designed structure consists of periodically notched LN waveguide arrays that support guided-mode resonances (GMRs). Benefiting from significant near-field enhancement within large mode volumes at resonance, a maximum SHG conversion efficiency of η = 2.71 × 10⁻³ is achieved at a peak power density of 3.83 GW/cm², representing a 3,000-fold enhancement compared with an unstructured LN film of the same thickness. These results provide new insights into the future design of integrated and high-efficiency nonlinear optical devices.

Nonlinear frequency conversion in compact platforms has long been limited by phase matching constraints and reduced interaction lengths. Metasurfaces offer a promising path forward by confining light into subwavelength resonant structures, enhancing nonlinear interactions in ultrathin devices. Yet the field of nonlinear meta-optics faces a persistent dilemma: nonlocal metasurfaces deliver high efficiency but little wavefront flexibility, while local designs provide phase control at the cost of poor conversion efficiency. In this work, we tackle this challenge from two directions. We first introduce a single-layer nonlocal platform that harnesses symmetry breaking and resonant Pancharatnam–Berry phase control to achieve efficient nonlinear holography. We then demonstrate a bilayer nonlocal metasurface that enables independent nonlinear wavefront shaping from optically decoupled layers.

Nonlocal metasurfaces driven by femtosecond optical pulses offer unprecedented opportunities for ultrafast dynamic control of light at the nanoscale. The strong field enhancements associated with nonlocal resonances can lead to efficient modulation of the optical response of the metasurface on ultrafast timescales. Here, we present a theoretical investigation on photo-induced band unfolding, and demonstrate how to leverage this transient symmetry breaking in a heterostructure metasurface for ultrafast diffraction management.

The Faraday effect is a well-known nonreciprocal phenomenon in which a magnetic bias rotates the polarization of light in magneto-optical media by breaking time-reversal symmetry. However, magneto-optical materials are typically lossy, bulky and difficult to integrate into photonic platforms, motivating the search for magnet-free nonreciprocity. Here, we investigate the realization of an all-optical mechanism for nonreciprocal polarization rotation by leveraging Kerr nonlinearity in isotropic media. In this approach, two circularly polarized optical pumps with opposite handedness and slight frequency detuning generate a beating optical bias that breaks the degeneracy between the orthogonal polarization components of a linearly polarized probe. A Fabry-Perot resonator is designed to support two pump modes and a probe mode together with its sidebands. The nonlinear interactions inside the cavity are analyzed using full-wave numerical simulations, which confirm the emergence of a nonreciprocal Faraday-like rotation reaching up to one degree. Unlike previous magnet-free approaches, the proposed mechanism does not rely on material resonances, phase-matching conditions or coherence between the pumps and the probe, thus, provides a promising route toward compact, integrable, all-optical nonreciprocal photonic devices.

In this talk, I will present new results on extreme electromagnetic effects enabled by the interplay of time modulation, frequency dispersion (temporal nonlocality), and spatial dispersion (spatial nonlocality), including the emergence of infinite “momentum bandgaps” in nonlocal photonic time crystals and new opportunities for on-demand, efficient, broadband wave transformations.

We present an analysis that reveals the presence of a metric in time-varying media. Starting from Maxwell equations, we show that any model for the evolution dynamics of time-varying media, such as coupled-mode theory, must always involve a metric that embodies the stored energy of the system. This metric is essential to satisfy scattering-matrix pseudo-unitarity in time-varying media. In contrast, in time-invariant systems, such a metric can always be factored into the system’s state vector. This fact reveals a fundamental difference of time-varying media from time-invariant media, with implications on understating their behavior and developing accurate models of their responses.

Space-time varying systems offer unprecedented control over wave scattering. Yet, most related studies assume nondispersive materials. Here, we develop a general framework for scattering at space-time interfaces between dispersive media. Discarding forbidden frequency transitions and applying the theory to Drude and Lorentz media, we uncover an exotic family of dispersion-mediated space-time modes that may enable novel concepts and applications.

We present a generalized time-varying Drude model in which carrier density, effective mass, and collision rate evolve in time. The multi-domain permittivity reveals non-adiabatic and loss-driven effects, including temporal blurring, selective gating/anti-gating, and low-frequency reshaping. By extending current frameworks, this model may offer a tool for designing and fitting experiments.

By presenting a comprehensive interaction atlas of 10 prominent optical materials across 90 binary combinations, for the first time we categorize the resulting physical responses into three distinct regimes: Enhancement, Mixing, and Depression. Our results, derived from the Maxwell-Garnett effective medium theory incorporating dispersive corrections, provide a detailed discussion on the influential parameters governing the enhancement, mixing, and reduction of electrostriction. These findings offer a transformative approach to tailoring optoacoustic interactions for high-performance Brillouin lasers and advanced signal processing devices.

We present an interleaved patch-rod structure that creates a low-loss, nearly dispersionless biaxial metamaterial for wide-angle impedance matching (WAIM) in circularly polarized (CP) antenna arrays. By optimizing the multilayer biaxial tensors and the superstrate height, we achieve a remarkable wideband and wide-angle performance for both axial ratio and active S-parameter. The design maintains the axial ratio below 3 dB and the active S-parameter below -10 dB over a wide frequency and angular range, making it ideal for high-performance circularly polarized phased array antenna applications.

This study investigates the thermo-mechanical behavior of a thin multilayer metamaterial composite for Low Earth Orbit (LEO) satellite applications using finite element analysis. Severe orbital thermal cycling induces deformation and stresses due to coefficient of thermal expansion (CTE) mismatch between layers. Results show that increased adhesive compliance and bond-line thickness, particularly using a compliant silicone adhesive, significantly reduce interfacial stresses and delamination risk.

This paper presents a systematic methodology for synthesizing a compact set of entire-domain basis functions for the analysis of dense metasurfaces (MTSs) within the Method of Moments (MoM) framework. The compact set is extracted via singular value decomposition (SVD) of a data matrix constructed from periodic MoM solutions obtained with Rao–Wilton–Glisson (RWG) basis functions, sampled over frequency and wavevector directions along the dispersion curves. The dominant singular vectors define an optimal set of entire-domain basis functions that preserve edge singularities and accurately reproduce the electromagnetic behavior of the element. These functions represent optimal linear combinations of RWG functions and naturally match the physical degrees of freedom of the structure, reducing the MoM unknowns to only a few per element while maintaining accuracy. Once pre-computed for a reference geometry, the basis functions can be analytically rotated and scaled through spectral-domain transformations, enabling their direct reuse for geometrically transformed elements without repeated full-wave analyses. The method is validated on a two-dimensional array of double-anchor patches printed on a grounded dielectric substrate. The computed dispersion curves are validated against CST Eigenmode Solver results showing excellent agreement.

We present an adjoint-based inverse design framework for generating high-fidelity, uniform 2D flat-top beams using TiO2 metasurfaces. Utilizing variance-based regularization and a Max-Min optimization strategy, our approach suppresses intensity hotspots and enables simultaneous dual-wavelength (700 nm and 759 nm) beam shaping.

The time-domain adjoint method provides an efficient framework for optimizing complex dynamical systems. By performing only two measurements, a forward and an adjoint measurement, the sensitivity of the objective with respect to all system parameters can be obtained simultaneously, enabling extremely low computational cost. The optimization can be carried out in-situ, naturally incorporating measurement noise and environmental perturbations. Depending on the application, either system parameters such as cavities or excitation conditions such as the source waveform can be optimized. We demonstrate this approach experimentally using coupled electronic networks, showing that time-domain adjoint optimization enables effective control of wave dynamics and energy transfer in complex environments.

Not all material properties can be realized with periodic structures. Correlated disordered media can achieve transport properties unattainable in crystals, such as isotropic photonic bandgaps. I will present gyromorphs, a new class of functional disordered materials combining liquid-like translational disorder with quasi-long-range rotational order, induced by a ring of delta peaks in their structure factor. We predict that gyromorphs outperform all known isotropic photonic bandgap materials, opening a path to fine control over optical properties in non-crystalline media.

A broadband-electromagnetic-metamaterial camouflage is experimentally verified, which can conceal a triangular object on a scattering surface. The proposed camouflage consists of triple or single layer drilled hole acrylic metamaterials that are matched with isotropic refractive indices designed by transformation electromagnetics. From measurements of the magnitudes of backward scattering ratios, $| m{S11}|$, it is confirmed that the differences between the scatterings from the triangular-background surface and those from the triangular-target object of which the height is higher than that of the surface are reduced more than 10 dB in the frequency ranges from 8.34 to 9.66 GHz of which the fractional bandwidth is 14.67% and from 8.53 to 9.5 GHz of which the fractional bandwidth is 10.76% for the transverse electric and the transverse magnetic polarizations, respectively, after applying the fabricated-metamaterial camouflage on the target object.

This paper presents an experimental characterization of a three-dimensional periodic bulk structure in the X-band. Numerical simulations reveal a polarization-dependent response consistent with excitation of a longitudinal plasma mode and free-space measurements confirms this result for horizontal polarization. The first Bragg condition occurs above the measured band, supporting the effective medium approximation. The observed behavior is consistent with an epsilon-negative regime near the artificial plasma frequency.

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We present a reconfigurable near-infrared optical filter based on a semi-circular periodic silicon grating integrated with phase-change Sb2S3. Finite element simulations under TE and TM polarizations demonstrate polarization-dependent transmission and phase-induced spectral shifts, enabling tunable resonance control, compact CMOS compatibility, and promising applications in photonics and infrared sensing.

A tunable plasmonic filter, operating in the infrared, based on a metal–insulator–metal (MIM) waveguide laterally coupled to a circular ring resonator filled with an electro-optic material is proposed and numerically investigated. The inner radius of the ring is varied, and electrical tuning is achieved by modifying the refractive index of the electro-optic region under applied voltages of 0–2V.

Micro-Doppler signatures play a central role in radar-based target recognition, as they arise from motion-induced electromagnetic scattering and encode information about the internal dynamics of observed objects. Despite the impressive performance of modern machine learning algorithms in target classification, such systems remain vulnerable to deceptive manipulation through deliberately engineered temporal modulation of the backscattered fields. In this work, we outline the physical foundations of passive micro-Doppler deception and experimentally demonstrate the ability to camouflage a drone as a helicopter from the perspective of an interrogating radar, while preserving complete radio silence. The proposed approach enables the realization of compact, low-cost, and low-power devices that can, for example, cause a flock of birds to be perceived as a swarm of drones by radar-based sensing platforms. The concept is naturally suited for implementation using passive time-dependent metasurfaces.

2π phase modulation with uniform reflectance remains a key challenge in tunable metasurface design. We propose and numerically demonstrate a mid-infrared metasurface that achieves continuous 2π phase modulation at λ = 7.41 μm under TM polarization by engineering a coupling between an overcoupled guided-mode resonance (GMR) and a graphene plasmonic (GP) mode. Electrically tuning the graphene Fermi level shifts the GP resonance across the fixed GMR frequency, inducing strong mode hybridization and phase repulsion while preserving uniform reflectance throughout the tuning range. The overcoupled GMR design ensures that hybridization redistributes the phase rather than suppressing amplitude, resulting in a near-circular trajectory of the reflection coefficient in the complex plane. The moderate-Q nature of the GMR reduces inter-pixel cross-talk, and combined with an inverse-design optimization framework enables effective beam steering and arbitrary wavefront shaping in the mid-infrared.

Hierarchical auxetic metamaterials often suffer from deformation incompatibility when combined with conventional cores, resulting in unstable buckling and irregular collapse. Inspired by the protective architecture of sea urchins, we propose a multilayer auxetic metamaterial integrating a re-entrant negative Poisson’s ratio lattice, a thin-walled tube, and a compressible foam core. The design preserves inward auxetic contraction while enabling coordinated volumetric compaction. Experiments and simulations reveal a transition from localized hinge-controlled folding to stable progressive collapse and distributed densification. The multilayer topology suppresses catastrophic localization and stabilizes deformation symmetry. The study demonstrates that deformation stability in hierarchical auxetic systems can be achieved through geometric compatibility rather than rigid confinement.

The electromagnetic response of a reconfigurable 12-12.5 GHz unit cell design is validated using a test coupon and a custom WR90 waveguide test fixture. The dual-polarized unit cell design uses two low-cost Skyworks SMV2202 varactors and demonstrates up to 180 degrees phase control with low loss.

We report the experimental observation of Fano resonance in a hybrid system of Copper nanoparticles embedded in a 3D Blue Phase Liquid Crystal scaffold. Using hyperspectral imaging, we demonstrate tunable resonant coupling between plasmonic scattering and Bragg reflection. This study provides a pathway for self-assembled and reconfigurable optical metamaterials.

Emerging photonic applications, ranging from optical computing and LiDAR to adaptive microscopy and dynamic holography increasingly demand high-speed, high-resolution wavefront control. In this field, metasurfaces have emerged as compact, scalable alternatives, enabling nanoscale control of light’s phase, amplitude, and polarization; however, these structures are typically static or only slowly tunable. In this work, we propose an alternative approach merging the fields of metasurfaces with the photonic integrated circuits realized on lithium niobate with an etch-free fabrication approach. In the photonic circuit, the infrared laser light is manipulated in amplitude and phase, at GHz speed, by electro-optic modulators and it is then coupled into free space by the metasurface with precise phase, amplitude, and polarization control. Our device will enable high-speed reconfiguration of complex wavefront while keeping a small, sub-cm², footprint.

This paper presents the design and experimental validation of a measurement test bench to characterize the large-signal behavior of finite grid oscillator (GO) arrays. The proposed setup uses a parallel-plate waveguide (PPW) with flared transitions to emulate ideal infinite-array boundary conditions, enforcing perfect electric (PEC) and equivalent perfect magnetic (PMC) boundaries. A one-dimensional rectangular GO array of 13 active E-PHEMT SAV-551 unit cells with sub-wavelength spacing (λ / 15 at 2 GHz) is investigated. The impedance characteristics of each active element are compared with the ideal infinite-array case using a root mean square error (RMSE) metric, which justifies the truncation of the array. The effect of edge padding and termination impedance is investigated. A reflector is placed within the PPW environment 7 cm away from the 1D GO. This enables injection locking and produces a stable oscillation at 2 GHz, as validated through both simulation and measurement.

We study the nonlinear transient response of detuned Helmholtz resonator chains subjected to impulsive excitation. Results demonstrate amplitude-dependent robustness mechanisms that challenge linear predictions, offering new perspectives on wave–metamaterial interaction and the engineering of structured media for extreme transient wave control.

The submitted work presents an efficient method for optimizing dispersive nonlinear transmission lines (NLTLs) for pulse synthesis with applications in radar, frequency comb generation, sampling, etc. The method identifies an adjoint system associated with a linearized model of the line to efficiently compute the gradient of all parameters which describe the NLTL by solving two problems per iteration. The first step is to solve the nonlinear problem for a given set of parameters, while the second is to calculate a so-called adjoint solution which enables the rapid computation of the gradient. The accuracy of the proposed method as well as the optimization of a representative, varactor-loaded ladder network is reported

Recent theoretical and experimental progress on light-matter interactions in time-varying media, and in Photonic Time-Crystals specifically, will be presented, including results on nonlinear frequency conversion and on interaction with atoms and with free electrons.

Light-matter interactions in time-modulated, frequency-dispersive, structured media can be drastically distinct from those in static media. We discuss the joint effect of dispersion and time-dependence on the scattering properties of nanostructures, their interaction with dipolar sources -that can become sinks-, and the existence of conservation laws in these time-dependent systems. We also introduce a quantum framework that incorporates dispersion and losses, as well as time modulation in a non-perturbative way. Our theory shows that both gain and loss must be accounted for to properly define the local density of states in time-varying media.

Time-varying metamaterials break energy and frequency conservation, unlocking novel wave control paradigms. We show how interferometric tailoring of wave-matter energy exchanges enables tunable gain, loss, and pulse shaping at temporal interfaces and in Floquet media, opening routes to efficient frequency conversion and Hong–Ou–Mandel–type correlations from classical light.

We present an analysis of the electromagnetic properties of waveguide-fed metamaterial elements. we show that a circuit model can be derived for resonant metamaterial elements, extending the results of a previous approach that considered non-resonant slot-like apertures. The model provides a simple, analytical expression that accurately captures the scattering characteristics of waveguide-fed metamaterial elements, and can be easily adapted to the co-integration of lumped components. We anticipate the approach can also be applied to advanced apertures, such as those incorporating gain.

We introduce a rigorous theoretical framework to calculate the total linear momentum transferred to arbitrarily-shaped scatterers by temporally-modulated electromagnetic plane waves. Unlike the traditional time-averaged harmonic analysis based on the Maxwell stress tensor, our approach utilizes the correlations of electromagnetic fields and the resulting momentum spectral density. We derive a fundamental relation that preserves the delicate balance between absorbed and scattered-field contributions to the total momentum, revealing that the Abraham force does not contribute to total momentum transfer. Our result assumes nothing about the material or geometric makeup of the scattering object, which can be active, nonlinear, bianisotropic and even time-dependent (including geometric deformations and material modulation). We use this theoretical framework to prove that drag (pulling) forces using complex frequency excitations cannot provide overall negative pull, since the total momentum transfer across the entire duration of the input signal must be positive. Finally, we demonstrate the ability to use this formalism to analytically derive the quasi-steady state instantaneous force on a passive particle, demonstrating a transient pulling force under complex frequency wave excitation.

A computation method for obtaining the principal limitations (fundamental bounds) of the polarizability tensor components of electrically small scatterers is developed. The tightness of the limit is discussed by comparing it with the known design of a magnetic metamaterial particle.

A scalar potential formulation for a spherical bianisotropic gyrotropic medium containing sources is developed. The analysis leads to two coupled Helmholtz-like equations having hybrid TE and TM field structure relative to the radial direction. Expected depolarizing dyads are identified which physically arise due to radial currents. Unexpected depolarizing dyads also occur from transverse currents. It is shown the unexpected depolarizing dyads are removable, leading to a mathematically and physically consistent theory.

This paper introduces an analytical model of the electromagnetic interaction between a plasma confined in a cylindrical cavity and a circular waveguide. Under appropriate assumptions, closed-form field solutions are obtained, offering insight into energy transfer mechanisms and the parameters that govern efficient cavity–plasma coupling.

We will discuss the creation of a Dirac point and linear dispersion in photonic band structure at the Brillouin zone center by breaking time reversal symmetry, resulting in an effective medium with zero refractive index. Such gyromagnetic zero index media have topological implications for both near field and far field wave behavior.

We present a wideband and lossless epsilon-and-mu-near-zero (EMNZ) metamaterials based on a composite structure consisting of dielectrics and non-Hermitian photonic structures (i.e., PT-symmetric metasurfaces). We also discuss the concept and practical implementation of this EMNZ metamaterials (e.g., zero-delay teleportation, supercoupling, and directive emission) in different spectral ranges.

We show that resonant non-Hermitian metasurfaces provide a novel route to chiral sensing, enabling the detection of extremely small quantities of chiral samples and the discrimination between different enantiomers through circular dichroism measurements.

Bound states in the continuum are localized waves that remain perfectly confined despite existing within a spectrum of radiating modes. We propose a method for determining the conditions under which bound states in the continuum emerge in metasurface cavities, formulated in terms of scalar electric surface impedance and scalar magnetic surface admittance. Full-wave simulations of two toroidal metasurface cavities are reported, illustrating the formation of single-mode quasi-bound states in the continuum and highlighting effectiveness and simplicity of the proposed approach.

We present theoretical and experimental findings on reconfigurable virtual metasurfaces based on nonlinear wave mixing in flat optics. Instead of relying solely on physical patterning, spatially structured illumination programs an effective nonlinear polarization distribution, enabling software-defined optical functionalities. We demonstrate dynamically tunable wavefront control and nonlinear image processing within a unified platform. This approach establishes a flexible route toward adaptive and programmable metasurface functionality beyond the constraints of linear optics. abstract here

Metasurfaces are a promising platform to enhance Spontaneous Parametric Down Conversion (SPDC). However, most devices in literature cannot control the generated photon pairs’ emission direction. We numerically demonstrate a bilayer metasurface that has tunable directional asymmetry in its photon pair emission, in addition to boosting SPDC efficiency via resonant enhancement.

We introduce an analytical synthesis method for nonlinear metagratings (MGs) exhibiting bistable diffraction, potentially enabling wireless beam switching through mild signal strength modulation. The framework, validated with full-wave simulations, identifies design parameters and guidelines for controlling hysteresis behavior, using Kerr-type nonlinear capacitive loads as meta-atoms. Important extensions to realistic varactor based implementations and transmissive beam manipulation nonlinear MGs are presented, forming a solid, physically insightful, framework for incorporating this appealing class of complex media in practical microwave applications.

Here, we demonstrate continuous-wave optical bistability in a silicon metasurface using symmetry-broken quasi-bound states in the continuum. High-Q resonances provide strong field confinement, enabling thermo-optic feedback. We show that symmetry breaking enables systematic tuning of the nonlinear switching thresholds, establishing dielectric metasurfaces as a platform for continuous-wave nonlinear functionalities.

Recent advances in metasurfaces and metastructures will be presented for achieving electromagnetic wave beam-steering and beam-shaping in the far zone.

We propose a diagnostic framework for reconfigurable intelligent surfaces (RISs) utilizing space-time-coding (STC) modulation. By implementing non-uniform frequency and orthogonal coding modulation strategies, the operational status of individual elements is mapped to distinct spectral harmonics or code channels. Experiments on 1-bit RIS prototypes confirm that these methods enable rapid and accurate fault localization via simple spectrum analysis, offering a scalable solution without computationally intensive algorithms or iterative measurements.

This work develops a semi-analytic formulation for the scattering analysis of infinite Reconfigurable Intelligent Surfaces (RIS) modeled as periodic arrays of reactive-loaded antennas. Using Floquet modal decomposition and discrete Fourier transforms, the approach enables calculation of reflection coefficients under both uniform and periodic loading. The framework extracts scattering parameters from single-cell simulations and supports design of RIS-based reflectors with controllable phase profiles. Validation against full-wave CST simulations for an 8-element dipole array demonstrates excellent agreement and successful excitation of desired Floquet modes through both local approximation and optimization-based methods.

This investigation proposes two reconfigurable metasurface antennas (MTSs), based on varactor diodes, for controlling the radiation of transverse electric (TE) surface waves (SWs). The proposed implementations, namely the Multiple-Control MTS and the Single-Control MTS, are characterized by low power consumption, simplified biasing schemes, and reduced control complexity. The realization of reconfigurable TE channels, capable of operating over a frequency band centered at $f = 5.9$ GHz and enabled by varactor diodes, is discussed. Full-wave simulations demonstrate a broad range of achievable propagation constant values through the varactors, along with versatile control of the leaky-wave (LW) aperture field. These features make the proposed MTSs attractive candidates for integration within a combined TE/TM channel architecture for dual-polarized systems, as beam scanning can also be achieved using these structures over a competitive operational bandwidth.

We present a general method to bound the singular values (channel amplitudes) of the scattering matrix of arbitrarily structured linear photonic systems. This decomposition provides a convenient approach to investigate maximal optical control of information-theoretic quantities (Shannon capacity, Fisher information, imaging limits) and power quantities (density of states enhancements, heat transfer). As an illustration of the framework, we compute ordered channel bounds for problems relating to communication through waveguides and metasurfaces, planewave detection, and radiative heat transfer.

Reconfigurable microwave systems such as dynamic metasurface antennas (DMAs) or reconfigurable intelligent surfaces (RISs) emerge as a technological enabler of next-generation wireless communications, sensing, and wave-domain computing. Despite many theoretical works and some antenna-level prototypes, system-level experiments notoriously struggle with model-reality mismatch due to fabrication inaccuracies and/or unknown system details. In-software optimization of the configuration of an experimental prototype to achieve a desired functionality, or determining fundamental limits to the achievable functionalities of a given prototype, remains difficult. In this talk, I will present an update on our recent efforts to establish a four-step universal framework for controlling waves in such reconfigurable microwave systems. First, we formulate a physics-consistent system model. Second, we experimentally estimate its parameters to minimize model-reality mismatch. Third, we perform in-software model-based optimization of the system configuration to approximate a desired transfer function. Fourth, we derive fundamental model-based bounds on achievable functionalities. Along the way, I will also discuss some ideas for maximizing wave-domain flexibility with enhanced mutual coupling, non-local programmability, and time-modulation of tunable components.

Programmable and self-configuring Mach-Zehnder interferometer meshes, previously exploited for processing coherent spatial modes, now can make programmable and self-configuring complex and multilayer spectral filters and, for the first time, can separate partially coherent light into its fundamental mutually orthogonal and mutually incoherent components, opening new opportunities in optical processing.

We utilize an information-theoretic perspective to analyze and design hybrid optical-electronic computing systems. Specifically, we reveal that well-designed linear meta-optical pre-processing elements reshape the input data distribution to improve performance on the task, similar to linear discriminant analysis. We also show that image recognition performance can be recovered after using (imperfect) nonlocal optics for space compression.

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Topological concepts have been at the forefront of materials research in recent years, driving a revolution in our understanding of the response of quantum materials and enabling new ways to manipulate light and sound in topological metamaterials. Topological defects and topological boundaries of different dimensions have driven a paradigm shift in photonics, where topological photonic crystals and metamaterials can be engineered to create one-way flow of energy robust to defects or to control such flows with synthetic degrees of freedom along topological domain walls. More recently, topological point singularities encoded into photonic structures have been shown to enable confinement of optical modes with the topologically nontrivial nature of the cavity imprinted into the vorticity of optical far fields. Here we demonstrate that the two latter concepts - domain wall and point singularities - can be unified into an even more powerful tool to enable arbitrarily shaped resonant cavities of any dimension supporting spectrally stable “zero-energy” modes. We experimentally confirm that such modes, whose existence is guaranteed by topological principles, allow an unprecedented degree of control over the optical field, which appears to have no phase modulation across space, can have any desirable radiation pattern, and enables spectral stability regardless of shape or length.

We show that space-time symmetries persist in crystals with travelling-wave modulations whose velocities can be either lower (subluminal) or higher (superluminal) than the speed of light, which enable the study of their topological properties and the prediction of spatiotemporal interface states.

<p> Inspired by the discoveries of topological phenomenain solid state systems, the study of topology in the propagation of light in photonic crystals has been the subject of much recent attention. Among all topological states of matter, time-reversal symmetry (TRS) broken topological materials, such as Chern insulators have been a particular focus due to their topologically protected unidirectional edge states with non-reciprocal propagation properties. In these systems, scattering processes from one boundary state into another are strongly suppressed, due to decoupling of counter-propagating 1D chiral edge channels. In this contribution, we will firstly introduce a general strategy to design 3D Chern insulating cubic photonic crystals in a weakly TRS broken environment with orientable and arbitrarily large Chern vectors. [1] Secondly, will show how these designs can be used to build photonic axion insulators. [2] Such a 3D topological photonic crystal exhibits extraordinary properties such as half-quantized surface effects and unidirectional chiral hinge states that propagate exclusively along the edges. These chiral hinge states form intricate networks that enable light to travel without loss or interference, even when obstacles are present. This breakthrough offers a deeper understanding of exotic particles and paves the way for practical applications in quantum computing, advanced sensors or in the development of axion-like particle detectors such as axion dark matter particles [3].</p>

We study localized electromagnetic surface waves at the interface between a uniaxial hyperbolic material and an isotropic topological insulator. The topological magnetoelectric coupling hybridizes TE and TM polarizations through modified boundary conditions. Analytical dispersion relations are derived for two relevant orientations of the optical axis: tangential to the interface and orthogonal to the propagation direction, and normal to the interface. We identify the corresponding existence domains and analyze localization through penetration depths into both media. The results reveal finite spectral windows of surface-wave propagation separated by forbidden frequency intervals, as well as frequency ranges where the mode loses surface character due to diverging penetration depth.

In this presentation, I will review the topologically protected phase modulation mechanism capable of achieving full 2π phase shifts with near-unity efficiency by encircling zero singularities in the parameter space.

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Metasurfaces based on toroidal and flattened wire knot elements enable unique control of electromagnetic waves. We show how their topology enables polarization rotation and chiral effects. We discuss practical design considerations, modeling, and propose extensions for applications such as selective absorption and beam steering.

We demonstrate that heterogeneous double-wire metamaterials—comprising two dissimilar and nonconnected wire arrays—enable loss-asymmetric hyperbolic dispersion and strongly asymmetric negative refraction. Due to their strongly nonlocal response and engineered microstructure, these systems support two independent propagation channels with unequal losses. Free-space waves incident at opposite angles preferentially excite different channels, rendering the system inherently angularly selective. As a result, strongly asymmetric negative refraction—characterized by pronounced angular asymmetry in transmission and absorption—emerges in these fully reciprocal metamaterials across microwave to infrared frequencies.

We present the synthesis of meta-atoms featuring angle-dependent transmission phase and all angle reflectionless behaviour. Utilizing the generalized sheet transition conditions, we demonstrate that meta-atoms characterized by a finite anisotropic magnetic surface susceptibility component $chi_{mathrm{mm}}^{xz} e0$ can achieve antisymmetric transmission phase with respect to the angle of incidence -- which always crosses zero under normal incidence -- maintaining unitary transmission. As a physical implementation of such meta-atoms, we propose a configuration of two tilted loops with capacitive loads. Numerical simulations confirm that adjusting the lumped capacitors within these loops allows for control of the $chi_{mathrm{mm}}^{xz}$ value; increase in the former leads to a higher phase shift experienced by the obliquely incident wave. Beyond physical insights, the proposed meta-atom can potentially be used as a building block of multi-angular metasurfaces: beam expanders, multiplexers, and devices for scan-range extension of phased arrays.

Chiral metasurfaces enable symmetry-controlled light–matter interactions, but combining strong chirality with rotational symmetry in nonlinear optics remains challenging. We develop a framework for all-to-circular upconversion using maximally chiral quasi-BICs and symmetry-enforced selection rules, demonstrated in bilayer and planar metasurfaces, with scaling laws guiding compact circularly polarized harmonic generation.

We report circuit-loaded subwavelength structures referred to as waveform-selective metasurfaces that enable passive time-varying electromagnetic responses even at a fixed carrier frequency without any control electronics or an external direct-current (DC) supply. Although these structures provide a high degree of freedom for temporal wave control, the transition speed of the electromagnetic state is limited by the nature of the embedded circuits. Thus, this talk introduces another type of time-varying metasurface that offers ultrafast switchable electromagnetic responses without external DC supply. We show that these structures can be integrated into a range of applications, including communications, imaging, and sensing.

We introduce space-time coding conformal metasurfaces for dynamic electromagnetic wave control on curved surfaces. Using a semi-analytical model and hybrid synthesis, we achieve multifrequency beam steering and shaping. X-band experiments demonstrate anomalous reflection, beam splitting, and diffuse scattering across distinct harmonic orders.

In this study, we present a coupled mode theory framework for designing waveform-selective metasurfaces with time-dependent reflection characteristics. In addition, we demonstrate a waveform-selective rooftop cloak as a proof-of-concept application.

Magnet-free circulators based on switched resonators can operate at modulation frequencies far below the signal carrier, overcoming the fundamental scaling bottleneck of switched-capacitor schemes. We develop an analytical framework that yields closed-form performance bounds on the transmission–isolation trade-off, validated by experiment, offering a scalable route toward mmWave and sub-THz integrated nonreciprocal components.

We proposed a new type of wave-selective metasurfaces composed of the switching component and applied them to reconfigurable intelligent surfaces. In particular, this study evaluates the numerical and experimental switching responses.

<p> We present the main results of our recent studies on space–time modulated and reconfigurable metasurfaces for communication and radar systems, highlighting physical-layer processing enabled by digital coding and control. By acting directly on analogue electromagnetic signals, we show that the use of the metasurface-aided signal processing paradigm (i.e. hardware-based manipulation of signals using space-time modulated metasurfaces) allows reducing latency, hardware complexity, and power consumption compared to conventional digital-signal-processing-based architectures. In particular, we demonstrate radar functions, such as frequency conversion, Doppler compensation, direction-of-arrival estimation, false-target generation, RCS manipulation, harmonic generation, and propose a new paradigm of smart antennas (stand-alone radiators and antenna arrays) characterized by advanced beam shaping/steering capabilities.</p>

We demonstrate a chip-scale, gate-tunable light-emitting platform that integrates scalable monolayer MoS2 with a HfN plasmonic gate electrode. The favorable band alignment enables giant trion modulation, yielding a PL modulation depth of ~ 24%.

In this presentation, I will discuss two recent examples of how the unique tunability of exciton resonances in monolayer 2D semiconductors can be leveraged to achieve dynamic nanophotonic devices: (i) selective beam steering with an atomically thin binary blazed grating; (ii) amplitude modulation with a hybrid-2D metasurface through strong coupling.

By leveraging metasurfaces and 3R-stacked MoS2 crystals, we achieve 140× second-harmonic generation enhancement compared with unpatterned 3R-MoS2 flakes with the same thickness, enabling single-pass second-harmonic conversion efficiencies of ~10−4 over only 160-nm-thick metastructures at relevant telecom wavelengths.

Put your abstract hereHyperbolic media enable extreme control of electromagnetic waves due to their anisotropic dielectric response, supporting highly confined and directional optical modes. Here we investigate the nanophotonic properties of the layered van der Waals crystal MoOCl2, recently identified as a natural hyperbolic material in the visible spectral range.

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We experimentally realize a bosonic Kitaev chain by encoding the corresponding Hamiltonian in the resonant modes of a frequency comb. We harness the inherent nonreciprocal propagation of light in frequency space to detect a small microwave tone with a signal-to-noise ratio that scales exponentially with system size.

We report the first experimental emulation of fermionic wave packet dynamics in Lorentzian AdS spacetime using a photonic platform, thereby establishing an experimental route to directly probing dynamical bulk phenomena underlying holographic duality, and provide a scalable platform for exploring nonequilibrium quantum field dynamics in curved spacetimes.

By leveraging rotating patterns of space–time modulation that enable ultrafast rotation-like dynamics, here, we present unequivocal experimental evidence of access to the regime of extreme rotational Doppler shift and electromagnetic Zel’dovich amplification, in alignment with expectations for operation within the angular momentum gap of a time-like crystal.

Criticality and topology are both organizing principles of phase transitions. Using an acoustic metamaterial platform, we experimentally demonstrate a unifying scenario: a critical topological phase transition in which topology remains well defined and becomes operative within the critical regime.

There is a growing realization that a material's fundamental properties can be radically transformed by placing it in an optical cavity.

We report exciton–polariton condensation in organic molecules strongly coupled to symmetry-protected bound states in the continuum (BICs) supported by dielectric and plasmonic metasurfaces. Condensation occurs in BICs with different modal characteristics. Remarkably, the thresholds are comparable for Ag and Si metasurfaces, despite the intrinsic losses of the plasmonic system.

This talk presents strongly coupled exciton–polariton states in van der Waals magnets and their potential for microwave-to-optical quantum transduction. I will highlight magnon-mediated nonlinear exciton interactions and approaches for controlling exciton-polariton propagation and confinement, outlining how these hybrid systems enable new opportunities for coherent light–matter coupling in quantum technologies.

Acoustoplasmonic metasurfaces comprise plasmonic nanoparticles which demonstrate enhanced polarization-sensitive absorption, which are leveraged to excite acoustic waves. We analytically and numerically examine this coupling of optical, thermoelastic, and acoustic mechanisms, and furthermore implement optimization algorithms for intelligent metasurface design. We finally turn our attention towards experimental realization of these studies.

Ability to enhance and dynamically control light-matter interactions at the nanoscale plays a pivotal role in the development of nanophotonics. Utilizing ultra-confined optical fields, ultra-strong electric fields and two-dimensional semiconductors inside electrically-driven single-crystal plasmonic nanocavities, we demonstrate active control of excitonic strong coupling and electroluminescence at the single nanocavity level.

Large-area silica hollow-spheres in photonic crystal films show a strong polarimetric response and offer an affordable, scalable, and versatile platform for new hybrid optical neural network technologies. Here we highlight results with compressive sensing and waveguiding towards applications with simple machine learning for high-speed transparent cameras.

We present the concept of coded-metasurface antennas as an enabling technology for compressive electromagnetic imaging and sensing applications. The coded-metasurface concept is used to synthesize spatio-temporally varying field patterns to probe and encode the channel information. It is shown that coded-metasurfaces can play a significant role in addressing some of the drawbacks associated with conventional electromagnetic imaging and sensing architectures, from simplifying the physical hardware layer to drastically reducing the number of measurements. We present and validate different modulation techniques as applied to coded-metasurfaces for a number of use case scenarios, including wireless communications, through-wall imaging, and security-screening as well as different near-field and far-field wave phenomena.

This study presents a compact, embedded RF metamaterial resonator for real-time monitoring of cement mortar hydration and damage. The S-shaped resonator, made on FR-4 and sealed in PET film, was placed inside a 150 mm mortar cube and monitored using a vector network analyzer during early hardening, water curing, and compression to failure. Changes in resonant frequency, quality factor, and minimum reflection were correlated with microstructural evolution and mechanical response. Results show high sensitivity to early-age hydration, clear curing trends over time, and distinct signatures during elastic and peak-stress stages, without affecting mortar strength.

We introduce a new class of piezoelectric metamaterial-based microelectromechanical systems (MEMS) that leverages topological physics to recognize complex microscale mass distributions. Unlike conventional resonant sensors, these devices support multiple topological interface states localized at different positions and frequencies, providing a spatially distributed but compact sensing framework.

We explore the possibility of using material and structural symmetries to create versatile platforms for reflectionless funneling and to route, concentrate, and sculpt electromagnetic wave as it propagates through designer metastructures.

While the global commercialization of the fifth-generation (5G) wireless communications is gradually taking off, there is already significant interest in the next generation of wireless communications. 6G scheduled to be launched in 2030, will provide a Tbps data rate, microsecond latency, and almost unlimited bandwidth to the connectivity of numerous mobile and intelligent networks. Antennas and metasurfaces are ubiquitous and indispensable components to generate and manipulate electromagnetic (EM) waves. In this talk, I will share the development and design of the space-time-coding metasurface antenna that can control all fundamental properties of EM waves, including amplitude, phase, polarization, frequency, and momentum. The space-time-coding metasurface antenna can further facilitate information manipulation, which can fundamentally simplify the architecture of information transmitter systems. The unparalleled wave and information manipulation capabilities of the metasurface antenna will spark a surge of applications from next-generation wireless systems, cognitive sensing to imaging.

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Impedance matching enables efficient power transfer but is fundamentally limited in bandwidth by the Bode–Fano bound for passive time-invariant networks. By introducing aperiodic temporal modulation of a capacitor, this limit can be surpassed while preserving the temporal shape of the transmitted signal, enabling broadband operation in resonant devices.

We analyze the optical response of frequency-dispersive particles whose permittivity is modulated in time. We focus on the symmetries and conserved quantities of the scatterer and demonstrate that the Floquet scattering matrix of this frequency-dispersive system is pseudounitary in the absence of material losses.

Using a Floquet–Mie formulation, we investigate electromagnetic scattering from a dielectric cylinder with periodically time-modulated permittivity. We show that temporal modulation induces parametric resonances linked to the intrinsic Mie modes and enables pronounced, tunable reshaping of the far-field radiation. Our results position time-modulated cylinders as promising meta-atoms for dynamically tunable metamaterials and metasurfaces.

In this presentation, we show how to establish bifurcation-induced nonreciprocity as a fully nonlinear route to topological-like mechanical functionality. This approach enables robust wave transport without magnetic fields, gyroscopes, or linear band topology.

Plate-lattice mechanical metamaterials offer exceptional stiffness-to-weight performance but remain limited by fabrication-induced imperfections and buckling. This invited talk presents a mechanics-based perspective showing how geometric design enables robust post-buckling behavior and programmable stability, opening pathways toward reliable and scalable metastructures.
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Related publication: https://doi.org/10.1016/j.eml.2021.101510

This talk explores the transformative potential of mechanical metamaterials in medical implants and robotics. We start by examining how finite dimensions shape the mechanical behavior of metamaterial-based structures. Building on this foundation, we discuss the application of metamaterials in the design of personalized implants undergoing linear elastic deformations and in soft robotic grippers experiencing geometrically nonlinear deformations. The talk concludes with insights into challenges and unique opportunities of translating metamaterial concepts into practical, real-world designs.

Kirigami and origami — the arts of cutting and folding — offer a route to mechanical metamaterials with large, programmable shape change. This talk explores how these and other shape-shifting structures can interact with e.g. airflow, light, and sound, enabling a class of climate-adaptive structures for a more self-regulating built environment.

This work demonstrates a compact metasurface–WS₂ platform that generates higher-order Poincaré spheres of arbitrary order by exploiting the full degrees of freedom of photons. In addition, a bijective mapping from the standard to the higher-order Poincaré sphere is theoretically verified. These results enable applications in optical communications, quantum information, and imaging.

We generate a magnetic skyrmion lattice via the Inverse Faraday Effect on a hexagonal plasmonic metasurface. The transfer of spin angular momentum induces drift currents in gold nanodisks, creating stable magnetic textures. This ultrafast, all-optical method paves the way for new architectures in next-gen spintronics and high-density data storage.

Recent research in optical, electromagnetic, and acoustical metamaterials has shown that spatiotemporal modulation of bulk properties and of interfaces between material domains can be used for unprecedented control of wave propagation and scattering. Spatiotemporal modulation of bulk properties has been used to enable nonreciprocal wave propagation in unbounded systems and to couple modes at different frequencies in bounded systems through frequency and wavenumber conversion. This work employs a Fourier series expansion-based coupled mode approach to investigate coupling between guided wave modes in an acoustic waveguide with different frequency-wavenumber pairs using spatiotemporal modulation of a single boundary. Results demonstrate the ability to couple incident plane waves to non-radiating (trapped) modes and to generate radiation from incident evanescent fields.

We study the scattering of waves at an interface whose properties vary in time, characterized by Drude-Lorentz dispersion with an abrupt change in its parameters. Our work uncovers an unusual mechanism in which novel frequency components are generated at the system's eigenfrequencies. A space–time interface enables several phenomena, including coupling between propagating and evanescent waves, as well as unexpected optical spin effects induced by phase conjugation.

A pulse shaping system is reported that consists of two reconfigurable phase shifters separated in space by a dispersive medium. Each phase shifter acts as a reflectionless, time-varying phase mask, imparting an aperiodic phase delay onto an incident pulse. The system can redistribute the temporal spectrum in transmission to form arbitrary complex envelopes (amplitude and phase). The required time-dependent transmission phase through each mask is determined using a modified Gerchberg-Saxton phase retrieval algorithm. A design example is presented in which an input pulse is both shaped and compressed in time. The results are verified using a commercial circuit solver.

Building upon the recent re-evaluation of boundary conditions at temporal interfaces, this work demonstrates that temporal metamaterials with passive and periodically impedance-matched modulation absorb electromagnetic waves with minimal reflection, acting analogously to perfectly matched layers. An effective medium model of the effect is provided. Wave absorption is validated through Floquet expansion method and FDTD simulations.

Over the last few years, there has been growing interest in using time- and shape-varying systems to explore new electromagnetic phenomena and develop innovative applications for communications systems. Accurate simulation of 3D electromagnetic structures with time-varying geometries or time-modulated material properties is a critical point to address proper design of next generation metamaterial-based devices, even though these dynamical systems present unique challenges. This work introduces a full-wave 3D electromagnetic solver based on the finite element method (FEM), to analyze the electromagnetic response of time- and shape varying 3D metamaterials.

Metamaterials were created by aligning complex nanoresonator miniarrays in periodic patterns using two types of dimerization and stacking them into quad-layers. During optimization asymmetry of constituent Babinet complementary bilayers and distinctly different orientation of ellipsoidal nanorings in the bounding convex layers was allowed. Bianisotropy enabled to achieve simultaneously asymmetric transmission and nonreciprocal rotation, proving isolator capability.

We propose a novel PTD-symmetric waveguide configuration based on gap-waveguide technology that overcomes key limitations of existing designs while preserving robust propagation. The structure features two edge lines excited by a single feed and incorporates a matching network to ensure proper impedance matching. It is fully compatible with gap waveguides. The design of the metasurface and the required feeding transitions are detailed, along with a simple microwave branching network achieving a 27.5% relative bandwidth with low reflection.

We develop a modal EFIE framework that directly extracts polarizability tensors of toru-knot particles from geometry. The trefoil knot naturally satisfies the chiral-Huygens condition, with a single current harmonic driving both electric and magnetic dipoles. This topology-driven response enables near-optical chirality in metasurface configurations.

We present an investigation of passive optical limiters (OLs) that utilize symmetry breaking of reflectionless scattering modes at exceptional points of degeneracy in nonlinear coupled-cavity systems. In our study, we analyze how structural parameters, including intercavity coupling strength and external losses, influence key performance metrics of these devices. Through numerical simulations and optical measurements, we demonstrate that tuning these parameters can effectively optimize the limiting threshold and operational bandwidth of the OLs. Furthermore, we show that increasing the fraction of nonlinear cavities enhances device performance in the nonlinear, broken-symmetry regime, resulting in a faster suppression of transmission. These findings indicate a pathway for developing compact, self-activating OLs with wide bandwidths and rapid response times, with critical applications in protecting sensors and vision systems from laser damage.

We analytically establish thermalization in a broad class of interacting second-order oscillator lattices with weak damping and weak nonlinearity. Unlike pseudo-Hermitian frameworks that require a conserved quadratic metric, thermalization here emerges from a variational envelope structure combined with time-scale separation, phase averaging, and kinetic closure, leading to a Rayleigh–Jeans spectrum with an explicit effective temperature determined by mechanical parameters. Because the effective thermodynamic variables depend directly on tunable quantities such as damping, stiffness, and nonlinear coefficients, the present framework provides a general design principle for predicting and controlling collective phenomena in large-scale engineering oscillator networks.

This paper presents an ultra-wideband electromagnetic metasurface absorber designed using genetic algorithm optimization. The absorber incorporates three metasurface layers between dielectric layers and glass fiber-reinforced plastic, backed by a perfect electric conductor reflector. The full-wave simulated result shows reflection losses below −10 dB with a fractional bandwidth of 170.4 % and a total thickness of 0.09 times a wavelength at the lowest frequency. This validates the broadband absorption characteristics, confirming the theoretical feasibility of the proposed design methodology.

The manipulation of electromagnetic (EM) waves has attracted increasing attention in recent years as modern wireless communication, sensing and imaging systems demand access to richer physical degrees of freedom for tailoring wave propagation. However, conventional metasurface antennas are usually constrained by their physical configurations and limited modulation mechanisms, which restrict the available degrees of freedom for wave manipulation. In this work, a space-time-coding (STC) conformal metasurface antenna is developed for reconfigurable control of EM waves from guided-wave propagation to free-space radiation.

The ability to manipulate polarization-dependent light–matter interactions is fundamental to modern photonic technologies, yet achieving strong and spectrally controllable optical responses remains challenging. Here, we investigate a one-dimensional all-dielectric photonic topological insulator (PTI) platform composed of alternating SiO₂-TiO₂ multilayer thin films for strengthening polarization-dependent light–matter interactions through spectrally engineered localized interface states. Through combined theoretical and experimental investigations, we establish the topological characteristics of the dielectric architecture and fabricate the PTI platform by using magnetron sputtering technique. The optical properties are characterized by generalized spectroscopic ellipsometry and correlated with finite-element electromagnetic simulations. In parallel, we present the fabrication and optical characterization of three-dimensional all dielectric nanoboomerang metamaterials prepared by glancing angle deposition, demonstrating pronounced anisotropic and chiroptical optical behavior. Together, these results establish the foundation for future hybrid topological–metamaterial architectures, where localized interface states can be spectrally matched with resonant modes to enhance birefringence, dichroism, optical activity, and other polarization-dependent light–matter interactions.

We study how switching the vertical boundaries between electric-wall (PEC/PEC) and magnetic-wall (PMC/PMC) conditions enforces vertical mode quantization and parity selection, which reorders and reindexes Bloch bands in Babinet-complementary hexagonal patch–ring bilayers. We also develop a minimal vertical-quantization model that predicts this band reordering and provides practical guidelines for comparing complementary layers and designing bilayers with controlled Dirac-cone placement and hybridization

This work presents tunable silicon metasurfaces based on quasi-bound states in the continuum for ultrafast and energy-efficient analog optical image processing. Femtosecond laser pumping enables rapid switching between edge-detection and bright-field imaging functionalities, offering a promising approach for integrated optoelectronic image-processing systems.

Over 80% of global energy production involves heat, yet conventional heat transfer—conduction, convection, and radiation—relies on temperature gradients that always drive energy from hot to cold. The fourth mode, thermal wave/resonance, breaks this paradigm. Arising from cross-coupling among transport processes within a medium, it enables isothermal heat transfer, and propagation against thermal gradients, all characterized by tunable, wave-like temperature distributions. Thermal-wave fluids are superconducting thermal metamaterials that harness this resonance, offering unprecedented efficiency and directional control. This presentation bridges theory and experiment to show how thermal-wave fluids outperform traditional modes, providing transformative solutions for energy, electronics, medicine, and environmental engineering.

Transparent conducting oxides operated near their crossover wavelength exhibit a low refractive index over a broad spectral window with strongly enhanced optical nonlinearities. In this regime, refractive-index changes approaching unity occur within tens of femtoseconds, enabling a near-ideal time-varying optical medium for ultrafast control of photon energy and momentum.

In this talk we first discuss quantum photonic integrated circuitry (qPIC) based on the recently discovered single-photon emitters in silicon nitride and the avalanche-enhanced optical modulation in silicon at single-photon intensities. Then, we show that transparent conducting oxides (TCOs) operating in the near-zero index (NZI) regime can provide strong single-light-cycle modulation, enabling novel optical phenomena in such extreme time-varying media, including photonic time crystals and 4D space-time metamaterials

The observation of time-reflection at optical frequencies has so far eluded the photonics community. Here, we demonstrate all-optical sub-cycle modulation of Indium Arsenide, measuring high levels of time-refraction for low pump intensities, and discuss experimental techniques bringing us closer to a first demonstration of time-reflection in the optical regime.

When a wave encounters a large abrupt change in the electromagnetic properties of the medium, it splits into time-reflected and time-refracted waves. Observing time-reflection requires order-unity refractive index variations occurring within less than a single cycle. Here, we report the first observation of time-reflection at optical frequencies.

Metamaterials have revolutionised the way we control light transport and generation. Yet, to date, they rely on static and passive architectures, only redistributing incident wave energy - for example a metalens that focuses light or a cloak that makes an object invisible. The next frontier lies in extending this control to the space-time domain, enabling waves to coherently interact with synthetically moving modulations. Here, I report the experimental observation of light scattering from optical modulations propagating faster than the speed of light [1], alongside coherent perfect absorption [2] — two phenomena that open a pathway to more complex spatio-temporal optical dynamics. I further present time-resolved measurements of the modulation profile in Indium Tin Oxide, uncovering ultrafast, non-monotonic dynamics [3] that give rise to strong time-varying optical effects. These are initial steps towards next-generation active metamaterials capable of manipulating light beyond the constraints of conventional, time-invariant designs.

We present a theory of fluctuational quantum electrodynamics of dispersive time-varying media. Crucially, our new framework accounts for the dispersion and losses of the time-modulated medium and furthermore, treats the temporal modulation in an exact manner, without relying on perturbative method.

We introduce information-optimal temporal states for probing localized events in dispersive time-varying media by maximizing Fisher information under energy and measurement constraints. For a modulated slab, the optimal probe outperforms optimized Gaussians and can precede the event, revealing the central role of temporal memory in waveform design.

Put your abstract hereThis study analyzes flexural wave reflections from time-modulated impedance boundaries using a semi-analytical framework based on Euler–Bernoulli beam theory. By modeling boundaries as temporally modulated spring elements, we derive expressions for reflected waves and explore how time-varying boundary conditions can enable advanced elastic wave control.

In this work, we theoretically propose that a Lorentzian temporal slab can serve as an ideal frequency sorter which separates the waves of different frequency components into different directions. We also demonstrate that the frequency sorter can operate at any momentum and incoming wave ratios by adjusting the controlling parameters.

The frequency degree of freedom of photons provides a versatile substrate for generating and manipulating novel electromagnetic states, including quantum states such as squeezed and entangled light. Here, we discuss how a comb of such entangled states can be generated using the frequency modes of a high-quality-factor microresonator through four-wave mixing nonlinearities. These quantum microcombs exhibit strong spectrally tunable squeezing across a wide frequency span exceeding 11 THz (100 nm). The same substrate also can be engineered to realize artificial lattice “materials” out of light, by coupling frequency modes to form synthetic dimensions. Our experiments on such frequency synthetic dimensions allow for direct probing of wave phenomena such as the non-Hermitian skin effect in 1D and 2D, both in real-space and momentum space. We conclude with perspectives for classical and quantum information processing using frequency-encoded synthetic dimensions.

We show how a strong laser-induced near field generated at a silicon metasurface dresses a 10 keV electron in a quantum-coherent superposition state, where the metasurface geometry controls the shape of the propagating electron wavepacket in space and time.

We study the impact of hidden symmetries on the dynamics of quantum photonic systems. We experimentally observe high-fidelity state transfer between latent-symmetric sites and suppression of two-photon coincidences between so-called singlet sites. We find that the introduction of multiphoton states and their (in)distinguishability can induce latent symmetries in asymmetric systems.

We introduce a cavity quantum electrodynamics platform where collective excitations of periodic quantum-emitter arrays strongly couple to the light modes of metasurfaces, giving rise to what we name crystal polaritons. We show that interactions between them can lead to a strong nonlinear response for extremely low polariton densities.

We demonstrate that the plasmonic response of noble metals can be extended well into the mid-infrared wavelength range by means of geometric dilution. By keeping minimum feature dimensions larger than the mean free path of electrons in noble metals but dramatically reducing the metal fill factor, mode confinement of λ0/35 and greater can be achieved in thin noble metal films. We show that not only do such materials offer strongly enhanced light-matter interaction at long wavelengths, but the lithographic control of plasmonic response opens the door to novel elliptical, hyperbolic, and canalized plasmonic modes.

The amount of power radiated by a source depends on its electromagnetic environment, captured by the local density of optical states (LDOS). However, conventional methods to calculate the LDOS yield divergences for sources embedded in inhomogeneous media. To overcome this limitation, we present a generalized expression that fully regularizes the problem and enables the calculation of the LDOS in arbitrary electromagnetic environments, including boundaries, loss, and gain.

We employ decoupled optical force nanoscopy combined with phase-informed decomposition to disentangle the photothermal force from mixed optical forces, thereby elucidating its physical origin. The chiroptical photothermal response of a chiral gold nanoparticle was observed under the illumination with opposite circularly polarized light. We also demonstrate that our system possesses a temperature sensitivity of 0.1 K. Building upon our decoupled optical force nanoscopy, we anticipate that the high-resolution photothermal measurements under ambient conditions provide a broad range of characterizing nanophotonic and semiconductor devices.

We demonstrate uniform hemispherical illumination from a concave metalens composed of GaN nanopillars with embedded InGaN quantum wells. A quadratic spatial phase profile (NA ≈ 1.4) creates a virtual point source that directs emitted light to fill the total internal reflection cone within the high-index substrate, coupling it uniformly into the free-space hemisphere. Fourier-plane imaging reveals 10–30% azimuthal and up to 15% zenithal uniformity enhancement over unpatterned thin films of equivalent area.

We experimentally probe the ultrafast dynamics of the nanoscale Inverse Faraday Effect to demonstrate unconventional magneto-optical responses. Using time-resolved MOKE, we characterize magnetization optically induced by linear polarization in plasmonic nanorods. Furthermore, we investigate chiral nanostructures generating magnetization exclusively under specific circular polarizations. These direct experimental validations pave the way for novel all-optical spintronic devices.

This manuscript presents a folded planar lens antenna, also referred to as a folded transmitarray, featuring an integrated subreflector based on Gregorian optics. Unlike conventional folded flat lenses, which typically require a polarization-rotating surface, the proposed antenna retains the fabrication simplicity of a standard non-folded planar lens while achieving a nearly threefold reduction in profile. The subreflector profile is derived in closed form using geometrical optics, resulting in an elliptical ring-like focus, which is realized as a planar reflectarray. Both the reflectarray and the planar lens aperture are implemented using the same three-metal-layer stack, supported by two dielectric substrates.

This paper proposes M-type ferrite based multi functional metasurface for LEO satellite communication. The proposed metasurface enables independent control of reflection at 17.5 GHz, transmission from 28 to 30 GHz, and absorption from 34 to 40 GHz within a single low profile platform.

Passive identification of objects using radar is of growing interest for automotive and autonomous systems operating at millimeter-wave frequencies. In this work, we introduce radar-readable QR codes implemented using engineered metasurfaces with frequency-dependent reflection phase gradients. When interrogated by an FMCW radar, the metasurface dispersion induces an artificial shift in the detected range, enabling information encoding without active transmission or onboard power. We develop the theoretical framework linking reflection phase dispersion to virtual range displacement, design and fabricate PCB-based metasurface pixels operating in the 76–81 GHz automotive band, and experimentally validate the concept in an anechoic chamber. Multiple QR-like patterns are demonstrated and successfully decoded. To assess scalability and robustness, convolutional neural networks are trained on augmented datasets, achieving reliable classification at moderate SNR levels. The proposed radar QR codes provide a pathway toward passive, infrastructure-independent identification for future autonomous mobility.

This work presents a fabrication-oriented multiphysics topology optimization framework that transforms continuous adjoint-designed dielectric metamaterials into manufacturable binary meta-structures. By combining electromagnetic adjoint and mechanical SIMP gradients with a converging coercion operator, the method achieves simultaneous gain enhancement and structural robustness in additively manufacturable dielectric devices.

This study presents a 300-GHz-band reconfigurable metalens combined with beamforming gradient metasurfaces (beam steering angles: 0°, 18°, 30°, and 38°). Near E field and data transmission links were evaluated in relation to the dynamic operation of the metalens, showing a significant boost in the received power and achieving data rates above 100 Gb/s.

We introduce a low-power optical kernel machine based on structural nonlinearity. By tuning the order of nonlinearity, we vary the kernel sensitivity and information capacity. We optimize the nonlinearity to approximate parity functions from first to fifth order for binary inputs.

Digital mechanical computers (e.g. bacus) dominated well into the twentieth century before being displaced by electronic machines. The decisive advantage of electronics was their transition to the nanoscale. Can nano-mechanical computers also be scaled to the nanoscale and compete with electronic architectures? We report the timetron as a central building block for mechanical computation based on the concept of a time crystal, which can be switched with femtojoule-scale energies and sustained with only a few femtowatts of optical power.

Analog optical processors promise low-latency, energy-efficient computation, yet remain limited by bulky optics, narrow bandwidths, and single-functionality designs. We present two compact visible-spectrum platforms an optimized multilayer thin-film spatial-frequency filter and a broadband TiO₂ metasurface performing edge detection and pattern recognition across 200 nm bandwidth. Together, these results establish a scalable path toward compact, low-power analog optical computing for imaging and sensing applications.

In this talk, I will discuss the recent progress of imaging, sensing, and display applications with mass-producible optical metalenses (visible, near-infrared). The basic principle, experimental demonstration, and scalable manufacturing methodologies will be presented.

We investigated the integration of various types of metasurfaces with epsilon-near-zero materials to enhance nonlinear optical signals. Both coupled-mode theory and near-field analysis of the hybridized modes were employed to examine the strong coupling effect and the symmetry relationship of the electric fields at the fundamental wave and up-conversion frequencies.

The emergence of MoOCl2 is offering new avenues to circumvent the limit of losses in plasmonics. We report a hybridization of plasmonic and waveguide modes within the material leading to high-Q surface plasmons. Surprisingly, we find in pump-probe experiments that optical pumping leads to an increase in the propagation length.

Optical power limiting and ultrafast switching are essential for protecting sensitive photonic systems from high-intensity radiation in advanced optical technologies. Recent progress in nanophotonics has highlighted intersubband polaritonic metasurfaces as a powerful platform for achieving exceptionally strong and ultrafast nonlinear optical responses through the coupling of resonant nanostructures with multi-quantum-well transitions. These systems have demonstrated high-contrast optical limiting, but existing designs are fundamentally reciprocal and therefore cannot provide direction-dependent protection or asymmetric signal routing. Here we show that nonreciprocal ultrafast power limiting can be achieved in transmission using engineered intersubband polaritonic metasurfaces that combine strong nonlinear saturation with structural asymmetry. This approach opens new opportunities for on-chip optical protection, asymmetric signal processing, and advanced nonlinear functionalities in next-generation photonic systems.

We propose that quantum geometry in topological materials provides intrinsic ultrafast spatiotemporal modulation. In optically pumped Weyl semimetals, anomalous-velocity feedback yields optical-frequency spacetime crystals, enabling unidirectional subgap light and ENZ parametric plasmon emission.

Here, we experimentally demonstrate momentum bandgaps arising in a passive photonic time crystal by leveraging time interfaces driven by commutated switching networks. We implement a passive PTC using an on-chip switched transmission-line-metamaterial in 65nm CMOS technology. This platform enables observation of passive PTCs that realize momentum selectivity without supporting parametric amplification.

Momentum bandgaps in photonic time crystals have drawn significant theoretical interest but limited experimental progress due to the need for high modulation speed and strength. We show that the speed constraint stems from the Manley–Rowe relations governing conventional modulation schemes. Modulating the plasma frequency of a Lorentz-dispersive material overcomes this limit, and adding a tailored spatial nonlocality enables infinite momentum bandgaps at arbitrarily low modulation speeds and strengths.

We investigate the interaction between a dipolar emitter and a dispersive photonic time crystal. By leveraging dispersion, we unveil the possibility of converting dipole emission into dipole absorption without relying on momentum gaps and while operating in the system’s stable regime.

Carrier Drift Modulation provides an ultrafast mechanism for inducing transient anisotropy in isotropic conductors, enabling hyperbolic dispersion and the formation of hyperbolic photonic time crystals. The same modulation supplies parametric gain that compensates intrinsic losses, offering a practical route to lossless hyperbolic media using existing semiconductor platforms.
Media link(s):

See preprint https://arxiv.org/pdf/2601.00547

In this contribution, we review new approaches that involve transferring highly efficient switching circuits, commonly used in power electronics, into the field of active meta-structures and antennas. This generalization may lead to highly efficient broadband RF positive impedance inverters (gyrators), and negative impedance converters or inverters. Finally, we discuss technological constraints such as maximum operating efficiency and power handling, and highlight future research directions.

We present a metasurface-enabled mmWave photonic limiter that preserves low insertion loss in normal operation while rapidly rejecting high-power interference. Subsecond activation is achieved by accelerating the thermally driven VO2 insulator-to-metal transition in a multilayer resonant stack using an ITO nanolayer and a subwavelength gold bow-tie antenna array to concentrate fields and localize heating, enabling fast switching in ~120 ms.

This contribution presents a simple experimental prototype of a gyrator-based Huygens radiator operating in the HF band (3 MHz–30 MHz) and reports preliminary results indicating extremely broad bandwidth and inherent non-reciprocal behavior.

A circuit-based metasurface with nonlocality and reconfigurability is proposed for multiuser orthogonal beamforming for multiple-input-multiple-output (MIMO) wireless communications. The metasurface features a low-profile structure, aimed for the application of satellite communications in the millimeter wave frequency bands.

A reconfigurable transmissive metasurface superstrate for wide-angle scanning of sparse antenna arrays is presented. The structure operates in two states: a refracting configuration that redirects a 30° radiated beam toward 60°, enabling radiation beyond the conventional grating-lobe free region, and a transparent configuration that preserves broadside radiation. The design combines an analytical microwave-network synthesis with a multi-objective full-wave optimization.

We demonstrate real-time wave control in nonlinear multi-resonant environments using time- and energy- efficient nonlinear adjoint optimization schemes. By exploiting nonlinear multipath scattering, small in-situ perturbations are amplified, enabling targeted channel emission, coherent perfect absorption and asymmetric transport. Our approach is applicable to in-door wireless technologies, imaging, power electronic and optical neural networks.

We analytically and numerically study wavepacket dynamics in a Hatano–Nelson type lattice. Using a continuum approximation, we derive closed-form expressions revealing three dynamical stages — acceleration, deceleration, and uniform motion — alongside a disorder-free non-Hermitian jump driven by momentum-dependent amplitude growth.

An acoustic standing wave creates an array of potential energy wells for sub-wavelength-scale objects. Trapped particles interact by exchanging scattered waves. Unless the particles have identical scattering properties, their wave-mediated interactions are nonreciprocal. Nonreciprocity enables pairs of mismatched particles to harvest energy from the wave to sustain steady-state oscillations despite viscous drag and the absence of periodic driving. We show in theory and experiment that this emergent steady state breaks spatiotemporal symmetry in a way that distinguishes it as a classical time crystal.

In this work, we present an experimental investigation of the generalized Wigner–Smith operator in non-Hermitian scattering systems. The resulting generalized response shares many features with complex time delay. For systems where multi-frequency measurements are not easily done, the generalized operator could be a powerful tool for system characterization.

Complex time delay (CTD) describes how long a wave lingers in a dispersive non-Hermitian scattering system. Here we demonstrate a connection between CTD and the temporal/spectral properties of a chirped Gaussian pulse, which can then be used to create a chirped pulse with broadband zero time delay.

<p> Over the last two decades, integrated photonics evolved from a technology platform for opticalcommunications into a powerful framework for engineering artificial photonic materials. Bycontrolling geometry, dimensionality, topology, and increasingly the temporal evolution ofoptical systems, photonic chips can now realize behaviors that have no counterpart inconventional optical media.In this talk, I will describe this evolution through examples spanning silicon photonics,dispersion engineering, nonlinear photonics, inverse-designed structures, syntheticdimensions, and spatiotemporally modulated systems. These advances reveal a transition frombuilding individual photonic devices toward creating programmable optical materials whoseproperties emerge from engineered interactions among many optical states. I will discuss howthis perspective opens new opportunities at the intersection of metamaterials, condensed-matterphysics, and integrated photonics, and may ultimately enable a new generation of photonictechnologies for communications, sensing, computing, and quantum information processing.</p>

I will present our group’s work on making programmable photonic metamaterials. After incorporating a photoconductor into a device containing a waveguide, it is possible to arbitrarily change the waveguide’s refractive index as a function of space, by shining an optical pattern onto the photoconductor from above. The scheme relies on the waveguide having a strong second-order nonlinear susceptibility, such as in lithium niobate. I will explain the working principle and present several examples of applications of our programmable linear metamaterial, spanning optical computing through communications. I will also show how we have applied the same approach to creating waveguide metamaterials for nonlinear optics, demonstrating spatial and spectral control of second-harmonic generation, and other nonlinear processes. Our work combines some of the benefits of metamaterials – the ability to create new or better functions – with some of the benefits of programmability – the ability to change function.

This work presents a coupled mode theory that describes wave phenomena and vibrations of coupled elastic systems for which the interface conditions are modulated as a function of space and time. We demonstrate the use of spatiotemporal modulation to couple modes, with applications focused on resonance control.

Quadratic-phase elastic metasurface with thickness-graded plate segments delivers diffraction-limited wide-angle focusing and maps incident momentum to laterally shifted foci. Integrated piezoelectric harvesting converts flexural-wave energy into self-powered robust vibration sensing.

We study synchronization-based information transmission through nonlinear scattering on a limit-cycle meta-atom. Information is encoded as a slow frequency variation of an incident carrier wave. A phase-reduced stochastic model shows when this variation is preserved (phase locked) versus degraded (noise-driven phase slips). The resulting criterion relates the locking potential barrier to the effective phase diffusion inherited from oscillator noise.

A temporal interface is a sudden change in the properties of the media hosting a propagating wave. Supported by experiments, we present a comprehensive theoretical framework demonstrating how temporal interfaces govern wavenumber and frequency composition. We further harness our framework to demonstrate a phononic time lens, and a classical analogue of dynamical quantum phase transitions.
Media link(s):

https://arxiv.org/abs/2601.08866

As one of the common structures in negative Poisson's ratio structures, the re-entrant honeycomb has been widely studied for its excellent negative Poisson's ratio and energy absorption capabilities. However, the traditional re-entrant honeycomb often exhibits low plateau stress and instability during compression, which limits its practical application. Therefore, in this paper, we propose a two-step design strategy for the rotation nonreciprocal enhanced re-entrant honeycomb (RNERH). The proposed design strategy yields a novel honeycomb with dual plateau stress and two dominant deformation modes. By adjusting the two design strategies, multiple adjustments to the different plateau stresses and plateau densification points of the structure are achieved, further revealing the influence of the two design strategies on the load transfer path of the structure. Additionally, we also investigate the relationship between the energy absorption capacity of the structure and the two deformation modes. The results show that the rotation angle θ2 can control the first plateau of the structure, and the optimal value is 35° for the overall energy absorption capacity of the structure. The relationship between l2 and the diagonal strut is the main factor affecting the second plateau of the structure, with the optimal parameter being 52mm. Through this two-step design strategy, the mechanical performance of the re-entrant structure is enhanced, and it also guides the design method of negative Poisson's ratio structures. This further compensates for the performance deficiencies of negative Poisson's ratio structures and promotes their practical application.

Distributed Acoustic Sensing (DAS) using optical fibers enables long-range detection of underwater acoustic signals but suffers from reduced sensitivity for sources located directly above the fiber due to predominantly transverse wave coupling. This limitation could be addressed by integrating DAS with an Underwater Acoustic Metamaterial Skin (UAMS), which can redirect incident acoustic waves to induce measurable axial strain via engineered wave phase gradients. An initial architectural design for a UAMS-enhanced DAS system is proposed, outlining the development of thin meta-atoms capable of precise underwater phase control to improve sensitivity for zenith-located sources.

We explore metasurface scattering motifs to tackle as main question: how can you realize a maximally informative scattering structure and experiment to report on deeply subwavelength dimensional or positional parameters such as structure placements, relative alignment and shape of nanoobjects. This is of main importance for the semiconductor industry, where the need is to quantify the lithography process. That industry currently uses optical scatterometry on gratings printed inbetween actual devices as a telltale proxy. I will show examples where we perform dark-field angle-resolved scatterometry on Fano-resonant structures, addressing how you objectively measure and optimize information content through design of geometry, input wavefront, mode structure and choice of observable.

We report the first spatial mapping of Fisher information flow in an optical position metrology experiment with a nanoscale target, revealing the flow’s topological structure, including singularities, vortices, and regions of information backflow.

A plasmonic metasurface based on Core-Shell-Like Nanostructures (CSLNs) enables precise nanogap engineering over macroscopic areas. Using a scalable modified nanosphere lithography approach, large arrays of CSLNs with nanogaps down to the single-nanometer regime were fabricated, exhibiting a core–shell-like optical response with multiple tunable plasmonic resonances spanning from the ultraviolet to the near-infrared. We demonstrate that nanogap-induced electromagnetic field enhancement governs both the optical and sensing performance, enabling highly sensitive and reproducible molecular detection, experimentally validated by surface-enhanced Raman scattering (SERS) spectroscopy.

We present a flat-object-plane hyperlens that enables non-contact super-resolution imaging by directly projecting subwavelength information into the far field. Unlike earlier-generation curved, contact-based hyperlenses, our design combines a planar multilayer section that converts evanescent waves into propagating modes with a surrounding cylindrical region that magnifies subwavelength features. The device is based on a silver/titanium pentoxide multilayer hyperbolic metamaterial operating in the Type I regime. Positioned 20 nm above the object, it preserves high spatial frequency information without direct sample contact. Experimental measurements of subwavelength objects demonstrate far-field resolution beyond the diffraction limit. This approach provides a practical pathway toward diffraction-unlimited projection imaging compatible with planar microscopy and nanophotonic platforms.

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We introduce a nonlinear sensing protocol based on synchronization of self‑oscillating meta‑atoms. We propose an alternative observable, the coherent spectral weight at the injection frequency, and show that it exhibits a threshold singularity with enhanced scaling compared to conventional frequency-splitting around square root degeneracies, including exceptional points. A toy acoustic experiment confirms three orders of magnitude enhancement in system response.

Achieving highly directive and spatially coherent thermal and luminescent radiation across broad spectral ranges remains a central challenge in photonics, particularly because conventional approaches to directional thermal emission often rely on narrowband resonances or polarization-specific mechanisms. Recent demonstrations of broadband directional emission based on Berreman modes have shown promising performance, yet their operation is fundamentally restricted to transverse-magnetic polarization, limiting their broader applicability

We investigate near-field radiative heat transfer mediated by surface modes in engineered hyperbolic sheets. We show that Lorentzian hyperbolic metasurfaces may provide extreme control over near-field thermal heat transfer. By tailoring the resonance bandwidth, detuning and shear anisotropy of the two sheets, we achieve highly super-Planckian heat flux and strong thermal rectification. Our results identify hyperbolic shear metasurfaces as a versatile platform for tunable nanoscale thermal management.

We experimentally investigate how nonreciprocity affects thermodynamic performance in laser-controlled nanomechanical resonator networks. Synthetic magnetic flux through time-modulated optical fields enable controlled coupling and frequency-conversion cooling. Phase-resolved fluctuation correlations reveal chiral, flux-tunable heat currents and energy redistribution. In the strong-coupling regime, broken time-reversal symmetry enhances refrigeration of a hot mode.

Thermal radiation and spontaneous emission emanate from fluctuations in dissipative materials. It is well known that such radiation can be manipulated in novel and unintuitive ways in advanced metamaterial environments, but modeling remains challenging. First, we discuss calculation of the spontaneous emission rate or LDOS in dissipative materials. We then present fundamental relationships between the emission and absorption in complex, nonreciprocal, and time-varying materials, and discuss resulting fundamental bounds.

We demonstrate a Kapitza-like mechanism in near-field radiative heat transfer: rapid modulation of a flux-controlling parameter generates a quadratic correction to slow thermal dynamics. This produces measurable temperature shifts and modified effective conductances, enabling active stabilization and control of nanoscale radiative heat flow.

The Smart Electromagnetic Environment (SEME) paradigm has emerged over the past decade as a key evolution trend in modern wireless system design, enabling the shaping of electromagnetic wave propagation to meet network performance requirements. This vision has stimulated the exploration of novel scenarios and design principles based on smart electromagnetic (EM) entities, including electromagnetic skins (EMSs). EMSs are passive, two-dimensional engineered surfaces capable of modifying wave propagation in indoor and outdoor environments through static or adaptive surface current control. Their relevance within SEME stems from advanced wave-manipulation capabilities (such as nonconventional reflection and beam steering) usually achieved via local tuning of the meta-atom EM response. Recent advances have further expanded EMS potential by addressing fundamental limitations, including the development of optically transparent and low-cost implementations suitable for seamless integration into existing structures, or their customization to integrated sensing and communications scenarios. This paper surveys recent progress in EMS engineering for SEME applications, focusing on state-of-the-art design methodologies and implementation strategies for next-generation wireless systems.

In this talk, we introduce wave-domain processing enabled by reconfigurable metasurfaces with the aim to redesign the physical layer of wireless communications. We will discuss the motivations, enabling technologies and our recent contributions in this emerging field of research.

Realizations of advanced electromagnetic functionalities in metasurfaces, based on strong non-local behavior, require fine subwavelength structuring, leading to practical complexities. We propose an alternative co-simulation design framework based on a coupling load network that eliminates this constraint by combining simple uniform arrays with tunable cascaded load networks.

Space-time coding metasurfaces enable programmable control of electromagnetic waves through joint spatial and temporal modulation, supporting harmonic generation, nonreciprocity, and waveform shaping. This talk reviews recent advances, highlighting smart propagation environments, integrated sensing and communications, conformal implementations, and reliability strategies for scalable, multifunctional intelligent surfaces.

In this talk, we propose clothes-embedded metasurfaces that convert incident-to-surface waves to focus into a device’s antenna located near the garment, boosting device connectivity by exploiting the larger textile area. The metasurface design consist of a loaded-wire metasurface topology, impedance matrix from numerical Green’s function values, and load optimization through multi-population genetic algorithm.

Mechanical metamaterials are often designed to control stiffness, waves, deformation, or stability, but their dynamics can also serve as a form of physical computation. In the first part of this talk, I will discuss our recent work on topological computation by non-Abelian braiding in classical metamaterials. We realize a mechanical analog of the one-dimensional Kitaev chain, in which tunable couplings support classical Majorana zero modes. By developing braiding protocols for arbitrary pairs of modes, the system reproduces braid-group statistics, implements single-qubit Clifford operations in a classical setting, and remains robust to mechanical defects through topological protection. This example shows how geometry and dynamics can encode computational operations directly in the material body. I will then use this result as a bridge to a broader question: beyond designing a material to perform a prescribed computation, can we train the intelligence of the body itself? In the second half of my talk, I will introduce a systematic way to train the intelligence of mechanical metamaterials, focusing on a specific capability of the material body: sensing. We call this capability sensing intelligence. We show that the geometry of a metamaterial body can be optimized to reshape external stimuli into internal signals that are easier for a neural network to interpret. Rather than hand-designing this physical preprocessing, we let the neural network train its own body for sensing by backpropagating the sensing loss to the body's design parameters through differentiable simulation. Across numerical and experimental sensing scenarios, the optimized body improves sensing accuracy by up to fivefold, accelerates neural-network training, and reduces the number of required electronic sensors by nearly an order of magnitude. Together, these studies point toward a broader framework of physical intelligence, where materials are not passive substrates for sensing and computation, but trainable partners of the brain.

In this talk, we present our recent work on the design and experimental demonstration of strongly coupled plasmonic-photonic ENZ nanostructures with enhanced effective nonlinearity driven by bound states in the continuum (BICs) in the classical and quantum regimes. Specifically, we address topological design and fabrication of on-chip nanocavities at multiple frequencies and engineered hybrid BIC Tamm-states structures for simultaneous trapping of pump and nonlinearly generated photons. Furthermore, we offer a perspective on single-photon nonlinear optics and quantum non-demolition (QND) detection in resonant nanostructures, rigorously accounting for realistic dispersion and material losses.

Metamaterials are a promising platform for a range of applications, from shock absorption to mechanical computing. These functionalities typically rely on floppy modes or mechanically frustrated loops, both of which are difficult to design. In particular, how to design multiple modes or loops with target deformations remains an open problem. We introduce a combinatorial approach that allows to create an arbitrarily large number of floppy modes and frustrated loops. The design freedom of the mode shapes enables to easily introduce kinematic incompatibility to turn them into frustrated loops. We demonstrate that floppy modes can be sequentially buckled by using a specific instance of elastoplastic buckling. We utilize our combinatorial floppy chains and frustrated loops to achieve matrix-vector multiplication in materia. Our findings bring about new principles for the design and use of floppiness and frustration in soft matter and metamaterials.

Light emission and absorption are typically constrained by the reciprocal relation of emissivity and absorptivity, as stated in the Kirchhoff’s law of thermal radiation. I will discuss our observation of strong nonreciprocal emission in a magneto-optical epsilon-near-zero metamaterial, points to new opportunities for heat flux control, energy harvesting, and sensing.

We propose an ultrafast optical modulator with lanthanum-doped barium stannate La-BaSnO3, where carrier-induced nonlinear response and tailored photonic band topology enable stable edge-state propagation. This approach provides defect-tolerant light manipulation within the perovskite transparent conductive oxide platforms, offering a promising route toward integrated and resilient nanophotonic devices.

We present a local and analytical form of Kramers–Kronig relations for linear systems. By describing the response function in terms of poles, residues and zeros, we directly link real and imaginary parts, overcoming bandwidth limitations and numerical challenges, first for a single resonance, then for general multipoles configurations.

We demonstrate a magneto-optical switch using tunable hyperbolic exciton-polaritons in CrSBr. Below 130 K, external magnetic fields trigger a topological transition in the polariton dispersion. Using nanostructured gratings for far-field excitation, we achieve significant optical modulation, establishing a platform for reconfigurable sub-diffractional devices and integrated photonic circuits.

We examine quantum emitters integrated with resonant van der Waals nanoantennas and metasurfaces to characterize nanoscale light–matter interactions. The enhancement is assessed in the weak-coupling regime, whereas strong coupling is analyzed through coherent emitter–antenna dynamics and entanglement, being linked to tunable emission and integrated quantum photonic functionalities.

The control of interactions among quantum emitters using nanophotonic structures offers significant opportunities for quantum technologies. Here, we introduce an approach based on a modified Langevin noise formalism that enables the description of the quantum dynamics of multiple quantum emitters coupled to complex, dispersive dielectric objects.

We numerically demodulate an amplified microwave signal using the spin-dependent fluorescence of NV− centers in diamond with on–off keying (OOK) encoding. A Lindblad master-equation model coupled to a two-mode Jaynes–Cummings cavity resonant with the 637 nm ZPL shows Purcell-enhanced emission shortens rise time, boosting the maximum bit rate from 7.73 to 96.15 Mbps.

We present a quantum electrodynamics approach to controlling spontaneous emission using time-modulated nanoantenna arrays. Combining a Floquet-harmonic Maxwell solver with Lindblad open-quantum dynamics, we study a barium-titanate (BTO) metal–insulator–metal nanoantenna platform coupled to a nitrogen vacancy center. Temporal modulation enables selective redistribution of emission among Floquet harmonics, yielding Purcell enhancements exceeding 5000. Using a 21-element array, radiation emission is directed to the +1 harmonic, achieving 88% coupling and 70% external quantum efficiency, along with directional beam steering.

We investigate the interaction between quantum emitters and multipolar antennas to explore light–matter dynamics at the nanoscale. Upon the weak-coupling regime, emission enhancement is quantified via the Purcell effect, strong coupling is investigated through emitter–nanoantenna interactions, and entanglement is evaluated using negativity, thereby demonstrating controllable radiation and potential for integrated quantum photonic applications.

Traditional 4f systems are indispensable for Fourier optics but their bulk poses a barrier to on-chip integration. We present a metapinhole architecture using metagratings to replicate angular filtering within a sub-wavelength footprint, reducing device volume by five orders of magnitude. By engineering two-dimensional dipolar resonances and Rayleigh anomalies, we realize high-efficiency transmissive low-pass, high-pass, and reflective band-pass filtering. This alignment-insensitive, lens-free platform could enable robust optical signal processing across the infrared, terahertz, and X-ray regimes.

We present an analysis of multi-user uplink MIMO communication systems employing stacked intelligent metasurfaces (SIM) as the transceiver at a base station. The SIM transceiver consists of cascaded metasurfaces, each with an array of subwavelength metamaterial elements that can be reconfigured individually. Conventional methods for analyzing SIM-MIMO systems rely on simplified electromagnetic models of metasurfaces to enable tractable system-level performance evaluations; however, such models lack the ability to accurately capture the electromagnetic responses of metasurfaces, potentially leading to inaccuracies in performance metrics. To address this limitation, we propose a systematic analysis framework for SIM-MIMO systems using a coupled dipole model of the SIM transceiver. Numerical simulations demonstrate the importance of incorporating electromagnetic-compliant characterization of metasurfaces in analyzing the system-level performance of SIM-MIMO systems.

This study proposes a hybrid metacomposite enabling simultaneous electromagnetic absorption and thermal radiation control. A magnetic composite layer provides impedance-matched microwave absorption, while a high-emissivity radiative layer enhances infrared emission within the atmospheric window. Preliminary electromagnetic and thermal characterizations demonstrate functional feasibility, and integrated multifunctional validation is currently underway.

In Low Earth Orbit (LEO), satellites exchange heat exclusively through radiation, requiring wavelength-selective control of solar absorption and infrared emission to maintain thermal stability. Conventional radiative coatings rely on metallic layers that inherently reflect microwave signals, limiting their direct integration with communication antennas. Here, we present an RF-transparent thermal metamaterial that enables simultaneous solar reflectance, mid-infrared emission, and microwave transmission within a single platform. By combining a spectrally selective metal–dielectric architecture with subwavelength slit patterning, the proposed structure achieves independent thermal and RF functionality. This multifunctional design provides a scalable pathway toward thermally robust metamaterial coatings for next-generation spaceborne communication systems.

Plasmonic metamaterial realization of a spatial Kramers–Kronig (KK) permittivity profile enabling near-perfect optical absorption was demonstrated. By tuning the major axis length of gold nanorods during numerical optimizations appropriately, the effective permittivity exhibits spatial Lorentzian dispersion and approximates a spatial KK-consistent distribution. The optimized multilayer achieves near-unity absorptance around 800 nm over a broad band. Time-domain simulations with 12 fs pulses confirm strong broadband absorption.

A log‑periodic toothed antenna with localized metamaterial loading is presented. Implemented on Kapton, two symmetric rectangular copper cells are placed near the tapered balun backside. This loading alters near fields, reducing VSWR and extending −10 dB S11 bandwidth, while preserving low profile, flexibility, and suitability for wearable systems.

This work presents the high-power behaviour of a fourth-order Ka-band bandpass (wideband) filter based on a locally resonant metamaterial (LRM) waveguide. The structure is a rectangular waveguide periodically loaded with metallic pins (resonators), operating below the cutoff frequency of the empty guide and supporting a TE10-like hybrid mode. A relative bandwidth of about 22 %, for an operating frequency f0 = 27.5 GHz, is obtained around Ka band with a four-pole response, and the power-handling (PH) capability is evaluated at the center frequency f0 and at the lower and upper group-delay frequencies peaks fTPG1 and fTPG2 . Using SPARK3D simulations with European Cooperation for Space Standardization (ECSS)- compliant total electron emission yield models for gold, silver, copper, and aluminum, we show that, in this under-cutoff LRM regime, the MP thresholds follow PMP(fTPG1 ) < PMP(f0) < PMP(fTPG2 ), in contrast with the behaviour usually expected in conventional filters. The MP avalanche region is also identified and discussed. The results provide new insight into the interplay between dispersion, stored energy, and MP in subwavelength meta-waveguide filters, and highlight the potential of LRM topologies for high-power Ka-band front ends. Experimental results will be presented during the conference.

Epoxy-based polymers are widely used in space structures due to their mechanical reliability and processing versatility. Under low Earth orbit (LEO) conditions, these materials are simultaneously exposed to high vacuum and ionizing radiation, which may alter their long- term performance. In this study, bisphenol-A epoxy(YD-128) cured with DETDA was experimentally evaluated under simulated LEO conditions combining ASTM E595-compliant high-vacuum exposure and proton irradiation. Vacuum testing performed at pressures down to 5 × 10⁻⁵ Torr revealed a systematic increase in total mass loss with increasing surface-to-volume ratio, reaching a variation of approximately 0.35% across the tested range. Proton irradiation at 20 MeV produced fluence-dependent discoloration, indicating radiation-induced modification of the material. The results demonstrate that geometric parameters and charged-particle exposure influence the environmental stability of epoxy polymers in LEO-relevant environments.

Electronically reconfigurable intelligent surfaces (RIS) offer a power-efficient solution for enhancing coverage, reducing latency, and enabling programmable propagation in emerging 6G wireless systems. This work presents a compact RIS unit-cell operating under circular polarization, formed by integrating four PIN diodes within a circular slot to realize a complementary split-ring resonator. The design achieves high reflection efficiency over 4.42–5.06 GHz (13.5% bandwidth) while providing 2-bit discrete phase control through diode state switching. The proposed approach enables low-loss, wideband, and fast reconfigurable beamforming suitable for scalable RIS deployments.

In this work we propose an antisymmetric dual-layer metamaterial approach for mmWaves to compensate for material thickness variations which have a parasitic influence on an in-plane shift-based sensor effect. We propose an antisymmetric alignment of broadside-coupled split ring resonators that compensates variations caused by manufacturing tolerances.

We have developed a novel form of amplification based on the non-Hermitian Berry phase. We describe its physical origin, and its demonstration in an optomechanical platform.

Wigner–Smith time delay becomes a complex quantity when applied to non-Hermitian systems with sub-unitary scattering matrices, and is directly connected to the poles and zeros of the scattering matrix. This complex generalization of time delay also applies to other quantities, including single elements of the scattering matrix, such as the reflection coefficient, or transmission coefficient between two scattering channels. We introduce a procedure utilizing complex time delay through which phase information, up to an overall constant, can be recovered from scalar reflection or transmission intensity data. We demonstrate the process with experimental data on a chaotic microwave scattering system, although the results apply to all forms of wave scattering.

We study two coupled resonators, one with saturable gain, one with loss, exhibiting multiple steady-state exceptional points. Near a third-order SS-EPD, oscillation frequency shows cubic-root sensitivity to perturbations. Optimal sensing occurs in the weakly coupled regime, enhancing response near this non-Hermitian degeneracy.

This presentation examines the physics of metal–dielectric thin films supporting Fano resonances. Interference between discrete and continuum modes in nanocavities reveals coupled oscillator behavior, producing semi transparent states where identical wavelengths are coherently partitioned between transmission and reflection.

Our ability to effectively tailor wave-matter interactions is of great practical importance with profound impact on societally important applications. Recently, notable efforts in the field of metamaterials have led to a range of functional devices, as well as remarkable physics enabling effective wave-matter interactions. Much of the attention was devoted to structures composed of single resonators and metasurfaces that support highly directive radiating and scattering responses, but also to platforms capable of localizing the fields through the excitation of bound states in the continuum. In this presentation, we review our recent and current efforts within super-directive lens antennas surpassing the known super-directivity bounds, and a wide scope of realistic and curvilinear metasurface cavities with both passive and active, electric and magnetic surface impedances, that enable enhanced and directional scattering, but also high field localizations inside the respective cavities.

P.T.D-symmetric systems are known to exhibit non-reflections into certain controlled modes. Realization of such systems, however, may pose significant technological challenges due to the need to synthesize magnetic or electric-magnetic materials with prescribed constitutive parameters over a wide frequency range. As long as the technology is not fully available, it is suggested to make use of media that approximate the desired behavior at the low frequency regime. A homogenization procedure for a realizable medium, presented below, provides a significant simplification for the design process. Results are backed by full wave simulations.

We present experimental demonstration of negative refraction using parity-time (PT) symmetric structures. We fabricated two passive metasurfaces and synthetically excited it with a complex-frequency signal, enabling tuning of virtual gain to achieve the PT-symmetry requirement. By measuring the transmission coefficient, negative phase accumulation as a function of frequency is observed.

Passive intermodulation (PIM) of rough conductors is studied as multiphysics effect. The main sources of RF signal distortions include the charge tunnelling, heat flow and mechanical deformations. The tunnelling effect is the fastest nonlinear process. The mechanical deformations and heat distribution are slower, but they are coupled to the charge tunnelling. The nonlinear analysis of PIM is performed for the conductor junctions and contacts of surfaces, deformed by the applied contact pressure. The explicit relations and their approximations are obtained for the PIM products in the contact joints of the compressed contact asperities.

I will discuss our recent development on conducting oxide and metallic nitride epsilon-near-zero materials in planar and optical fiber platforms. I will present the observation of abnormal nonlinear temporal dynamic of hot electrons and enhanced optical nonlinearity in AZO and ITO ENZ thin films under different pump fluences and excitation angles using a degenerate pump-probe spectroscopy technique. I will then discuss the development of 2D ITO ENZ materials via liquid metal printing technique and their electrically tunable properties. Finally, I will discuss the first experimental integration of ENZ materials and metasurfaces with optical fibers for efficient excitation of ENZ mode and advanced wavefront shaping.

Here we design and realize ultrathin periodically-poled structures and metasurfaces using highly nonlinear van der Waals semiconductors (3R-MoS₂) to demonstrate phase-matched and mode-matched nonlinear optical processes, respectively. By overcoming size-efficiency trade-offs, these ultracompact platforms enable efficient frequency conversion and entangled photon generation over microscopic pathlengths for on-chip photonic applications.

We demonstrate compact nonlinear and quantum plasmonic metasurfaces to efficiently generate second harmonic response from surface nonlinearities and control quantum single photon-photon interactions. Our findings demonstrate that ultrathin plasmonic metasurfaces can have potential applications in integrated nonlinear and quantum photonic systems.

We describe our photonic inverse design approach, and show how it can be employed to design high performance integrated photonics for applications including optical interconnects and quantum technologies. While we demonstrated inverse designed structures a variety of materials ranging from silicon, to silicon carbide, diamond, and titanium:sapphire, we also show that silicon inverse designs can be fabricated in commercial foundries where they experimentally outperform photonics PDK.

We demonstrate a nonlocal metasurface that simultaneously achieves extraordinary optical transmission (EOT) and full 2π phase control of the transmitted wavefront for circular polarizations. By applying Babinet's principle to a metasurface governed by a quasi-bound-state-in-the-continuum supporting geometric phase control, the supported high-Q resonance is mapped onto a complementary transmissive aperture geometry patterned on freestanding copper foil. The EOT phenomenon is mainly controlled by the aperture shape, while their rotation encodes an arbitrary geometric phase across the aperture without impacting the high-Q resonance. We demonstrate anomalous refraction at 19.5 GHz with a simulated EOT factor of ~6 and experimentally measured EOT factor of ~3, validated by free-space near-field measurements.

Monolithic metasurface stacking can miniaturize and add functionality to planar optics, but fabrication is limited by spacer non-planarity and incomplete gap filling on patterned surfaces. We study PECVD SiO₂ spacers, identify a planarization thickness and a void-formation regime for narrow gaps, and find little sensitivity to pattern density. As a demonstration, three-layer stacks preserve the combined resonance spectrum with a modest spectral shift, establishing a practical spacer process window for robust multilayer integration.

In this work, we analyze the impact of spatial dispersion in homogenized metasurface models and propose a general analysis methodology that incorporates spatial dispersion while preserving model simplicity and computational efficiency. The proposed framework is validated through numerical studies of metasurfaces implemented with different technologies, demonstrating improved predictive capability.

We present a general temporal coupled-mode theory framework for modeling strong mode hybridization in reciprocal and non-reciprocal bianisotropic metasurfaces. The formalism unifies omega and chiral responses in reciprocal systems, as well as artificial moving medium and Tellegen effects in non-reciprocal platforms. We derive the conditions required to achieve extreme-value functionalities, including asymmetric absorption, circular dichroism, and nonreciprocal directional dichroism.

A technique is presented for calculating the electromagnetic fields scattered and guided by spatially discrete, traveling-wave modulated metasurfaces under time-harmonic plane wave illumination. The technique uses multimodal network theory and the network parameters of the metasurface’s unit cell extracted using fullwave simulation. The technique is validated through commercial fullwave-circuit co-simulation.

Using GSTC, we derive analytical invisibility conditions for metasurfaces that achieve reflectionless, phase-preserving transmission, including oblique incidence, bianisotropy, and asymmetric media. Closed-form co-polarized susceptibility relations are obtained and validated with full-wave simulations.

A novel technique for shaping curved electromagnetic beams in the near field is presented, using distributed ray-caustics. The proposed method enables the synthesis of beams that propagate along arbitrarily prescribed trajectories, allowing controlled bending around known obstacles while preserving localized focusing features. Numerical simulations validate the proposed approach.

Sub-wavelength diffractive meta-optics have emerged as a versatile platform to manipulate light fields at will, thanks to their ultra-small form factor and flexible multifunctionalities. However, miniaturization and multimodality are typically compromised by reduction in imaging performance, thus meta-optics often yield lower resolution and stronger aberration compared to traditional refractive optics. Concurrently, computational approaches have become popular to improve the image quality of traditional cameras and exceed limitations posed by refractive lenses. This in turn often comes at the expense of higher power and latency and such systems are typically limited by availability of certain refractive optics. Limitations in both fields have thus sparked cross-disciplinary efforts to not only overcome these roadblocks, but to go beyond and provide synergistic meta-optical - digital solutions that surpass the potential of the individual components. I will present our research effort on meta-optical computational imaging, with particular focus on broadband imaging and low power/ latency computer vision. Additionally, I will discuss the opportunities and challenges of creating sub-wavelength spatial light modulators for imaging exploiting meta-optics.

This talk will focus on the use of meta-optics for implementing computation for edge sensors, serving to off-load computational operations from digital processing platforms focused on spatial and spectral pattern recognition.

To couple free-space modes on chip, the key challenge is not enhancing coupling rates, but rather avoiding unwanted couplings. We propose a pathway towards high-efficiency coupling of hundreds or thousands of modes. Furthermore, we describe information-theoretic considerations that call for a unique variation of grating coupler functionality.

Geometric phases have expanded the capabilities of optical devices to control both the spatial and momentum properties of light. We explore recent advances of both the detour phase and Pancharatnam's phase to control light in nonlocal metasurfaces and cavities.

We study a hexagonal bilayer formed by a PEC patch-island lattice and its ex-act Babinet-complementary percolating mesh (hexagonal aperture) lattice. Using the C3v little group at the K point, we identify the symmetry-enforced Dirac doublet in each layer and show that exact complementarity does not guarantee identical dispersions in a three-dimensional eigenmode environment. Finally, we develop a minimal two-band-per-layer coupled-Dirac model with detuning and interlayer hybridization to interpret the stacked bilayer dispersion and gap opening.

Disordered stealthy hyperuniform (SHU) dielectric slabs exhibit diffusive, localized, and bandgap transport regimes. Here we present numerical results based on large-scale finite- difference time-domain (FDTD) simulations, analyzing both the total transmission coefficient and the transverse spreading of a focused beam at the output plane. At frequencies far from the bandgap, rapid expansion of the intensity profile toward the slab edges indicates diffusive trans- port. In contrast, strong transverse confinement near the gap signals the presence of Anderson localization, Lifshitz tail states, or a photonic bandgap. These results establish beam-spreading analysis as a practical and versatile diagnostic tool for complex photonic materials, applicable to both numerical and experimental systems.

Hyperuniform systems are those whose density fluctuations scale more slowly than the volume of the system. This implies that the spectral density of such a pattern goes to zero at small momentum. Periodic crystals and quasicrystals are hyperuniform, as are disordered systems, provided the disorder is highly correlated. The problem of wave transport through hyperuniform systems is notoriously difficult to address in numerical simulations because of the extremely large system sizes required to establish definitive results. Here, I will present our analytical results on Lifshitz tails in the hyperuniform disordered Anderson model [1]; this addresses the question of the nature of the band gap in such systems, and to what extent hyperuniformity leads to greater band gaps. I will also present our experimental results on large two-dimensional photonic crystals with added stealthy-hyperuniform disorder [2], capturing the “stealthiness transition” and demonstrating both the presence of multiple scattering and the interplay with the non-Hermiticity that is necessarily present as a result of the radiative leakage. [1] Karcher, J. F., Gopalakrishnan, S. & Rechtsman, M. C. Effect of hyperuniform disorder on band gaps. Phys. Rev. B 110, 174205 (2024). [2] Barsukova, M. et al. Stealthy-hyperuniform wave dynamics in two-dimensional photonic crystals. Preprint at https://arxiv.org/abs/2507.05253 (2025).

Wave absorbers, notably Dallenbach layers, underpin antennas, EMC, and RCS reduction. Classical Rozanov bounds assume plane waves. We generalize thickness–bandwidth limits to broadband spatial spectra and curved surfaces, enabling further realistic absorber design.

Self-dual metasurfaces support degenerate TE and TM surface waves under a duality impedance condition. Radial modulation enables broadside radiation with independent polarization control via balanced Huygens excitation. We derive the exact electric–magnetic moment ratio and analytically balance leakage constants, providing a framework for efficient dual-polarized metasurface antennas.

We present a semianalytical scheme for the design of realistic Salisbury screens capable of wideband absorption. Building upon the concept of metagratings (MGs), we utilize associated rigorous analytical models and follow the guidelines recently proposed by Nayani et al. (Nat. Commun., vol. 16, 2025) to synthesize printed-circuit-board (PCB) MG absorbers with enhanced bandwidth. The proposed method, validated via full-wave simulations, yields fabrication-ready layouts for Salisbury screens with improved frequency response, while offering analytical insights on the relation between concrete degrees of freedom in detailed PCB absorber designs and the path to increase their performance in light of the Rozanov bound.

An azimuthally isotropic wide flat-top embedded element gain pattern (EEGP) is ideal for improving the embedded element efficiency (EEE) in dense array configurations. Conventional Fabry–Perot (FP) resonant antennas, typically produce radiation patterns with asymmetry between the E- and H-planes due to polarization-dependent resonance behavior. In this work, a FP structure composed of electromagnetically matched dual media is proposed. By employing media with equal relative permittivity and permeability, the FP resonance becomes polarization independent. As a result, the structure produces a far-field power pattern that is isotropic with respect to the azimuthal angle, enabling the realization of a wide flat-top EEGP suitable for high-EEE dense array applications.

The scattering matrix imposes constraints on input-output relations in linear wave systems. By introducing additional constraints, scattering processes can be formulated as non-Hermitian eigenvalue problems with discrete complex eigenfrequencies, known as critically constrained scattering modes (CCONs). It is now well understood that these complex frequencies can be excited transiently, focusing on either resonances or zeros of the scattering matrix. Recently other complex eigenspectra have been studied for coherent control of scattering, e.g. for reflectionless excitation and more constrained problems such as routing, when they are tuned to the real axis. Here we demonstrate that coherent control such as wave routing can be achieved even for complex eigenfrequencies via transient (complex frequency) excitation. Our results establish CCONs as a general framework for manipulating temporally structured waveforms in generic resonant systems.

The optical theorem dictates that the forward scattering of an object is proportional to its total extinction. Consequently, for passive objects illuminated by continuous waves, zero forward scattering implies complete transparency - no scattering and no absorption. While active materials have been proposed to suppress shadows while maintaining scattering in other directions, they suffer from inherent instabilities. Here, we experimentally demonstrate shadowless forward scattering from a macroscopic high-index dielectric sphere by exciting it with a complex-frequency (CF) wave. By tailoring the temporal decay of the incident pulse to mimic the response of a gain medium (virtual gain), we achieve a 26 dB suppression of forward scattering compared to standard continuous-wave excitation, without using any active materials.

<p> We find analytic (closed-form) expressions for the complex surface conductivities re- quired to absorb coherent (subwavelength) spherical and cylindrical wavefronts by coupling to the surface plasmon resonances of isolated nanoparticles. We extend our formalism to the case of periodic arrays of coupled scatterers and find similar closed-form expressions. We show that the complex surface conductivities reported herein may be easily achieved in moderately doped graphene.</p>

In this talk, we present a framework for achieving bandpass filtering and broadband perfect wave transmission in complex systems by optimizing symmetric disordered media via inverse design. We show that leveraging symmetry of complex media reduces the optimization’s complexity enabling the incorporation of additional constraints in the parameter space. Numerical simulations based on the coupled dipole approximation are validated experimentally in a multimode microwave waveguide with dielectric and metallic scatterers.

This work proposes a novel design for a reconfigurable polarization-conversion metasurface operating for adaptive radar cross section (RCS) control in the X-Band. This func- tionality is achieved through unit cells that can be independently configured as either opposite phase polarization conversion (PC) or as two oppositely phased Artificial Magnetic Conductors (AMC). Simulation results demonstrate a 10 dB reduction in RCS of nearly full X-Band. Practi- cal constraints related to the control mechanism and manufacturability are also considered, and their impact on the metasurface design is briefly discussed.

Radiation forces enable contactless acoustic/electromagnetic manipulation, but multiple scattering makes robust control – especially of several objects with competing goals – hard. We map force objectives to Hermitian operators built from the scattering matrix: eigenstates give optimal single-object actuation, while multi-object problems yield Pareto fronts and exact trade-off bounds, echoing incompatible quantum observables.
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See our arXiv preprint: arxiv.org/abs/2511.22279

Hybrid quantum defects in wide-bandgap nitrides enable tunable single-photon emission through nonlocal donor–acceptor recombination coupled to molecular vibronic modes. We establish a microscopic framework linking vibronic structure, spectral variability, and nonlocal recombination processes, providing design principles for spectrally programmable quantum light sources compatible with integrated nanophotonic and metamaterial platforms.

Local electromagnetic fields can be strongly modified using artificially structured materials, in particular cavities with small gaps between two metal interfaces can support extreme local field enhancements. Using this, we demonstrate picosecond single photon emission from SiVs in diamond and Purcell factors greater than 10,000 for single colloidal quantum dots emitting in the telecom band at 1550 nm.

In this work, we have introduced a novel platform and a methodology to precisely control and investigate spontaneous emission lifetimes at the nanoscale. Our technique enables detailed observation of light-matter interactions beyond the diffraction limit, facilitating molecular localization with nanometric precision, and allowing for single-molecule-level interrogation and ultra-precise nano-positioning analysis. Our approach reveals unprecedented, high non-averaged Purcell factors, demonstrating significant potential for quantum applications and sensing technologies.
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Controlling light-matter interactions at scales smaller than the diffraction limit at the single photon level is a critical challenge to advancing quantum technologies and sensing applications. Single-molecule nanophononics is an emerging field offering exciting opportunities to investigate light-matter interactions at the emitter level with nanometer-scale resolution.

We proposed a non-invasive methodology, capable of temporally and spatially correlating enhanced molecular single-emitter properties coupled to a novel material platform that enables precise engineering of spontaneous emission.  This platform is based on freestanding hollow plasmonic nanocones arranged in a square lattice, uniformly scalable to the centimeter scale while maintaining unitary cell geometry. Exhibits diverse and tunable light-matter interaction enhancement properties in function of the out-of-plane illumination angle.  Significantly increasing the local density of states (LDOS) in a manner that depends on both emitter position and dipole orientation, offering extreme position sensitivity within the 3D electromagnetic landscape. The strong changes in the emission of molecular single emitters along the 3D nanofields in the metamaterial, leads to billions of Purcell-enhanced single emitters integrated into a single nanodevice. We measured the LDOS modification along the 3D fields with nano precision and single emitter level. Implementing a non-scanning widefield method combining far-field single-molecule super-resolution microscopy, with time correlation single photon counting (TCSPC), we probe molecule per molecule enhanced quantum light-matter interactions. 

 

These unique properties offer an exceptionally sensitive platform for molecular sensing and the detection of small vectorial field variations with resolution surpassing the diffraction limit. By leveraging these plasmonic nanostructures and our method for measuring single-molecule Purcell-enhanced nano-resolved maps, we enable fine-tuned control of light-matter interactions. Obtaining fast single-photon sources at room temperature, provides a powerful tool for quantum applications at the single-emitter level. Our results heralds advances in technologies limited by resolution, single-photon efficiency, sensitive detection, scalability, low-density sensing, and vectorial field mapping.

 

We report the active gating of photon avalanching via the optical magnetic field. By modulating the magnetic ignition in thulium ions, we decouple the threshold from cooperativity, achieving a record non-linearity (s=62). This establishes the magnetic field as a key lever for collective quantum dynamics and adaptive neuromorphic photonics.

The fields of Vibrational Mechanics and Vibrational Resonance were born after Kapitza’s explanation of the stability of the inverted pendulum. Inspired by these concepts, we have been exploring how approaches from these fields can introduce novel and interesting phenomena into the field of metamaterials. In this talk, I present an overview of our recent findings in “Vibrational Electromagnetics” through a series of investigations of wave-matter interaction in certain metastructures, including specially designed inhomogeneous metamaterials, non-Foster structures, non-Hermitian metastructures, structured diffusion, and manipulated optical rays, among others. I discuss some of the physical insights into our findings and also forecast future possibilities in this field

Advances in space–time modulated metamaterials have enabled synthetic motion, partially reproducing electro- magnetic signatures of moving objects without physical displacement. We evaluate how faithfully synthetic motion reproduces genuine motion using Galilean and Lorentz modulation protocols. By analysing wave scattering properties and hybrid motion (both real and synthetic motion simultaneously), we identify which dynamical effects are reproduced and which remain intrinsically tied to true physical motion.

Materials with unusual optical properties enable advanced control of light but are often rare or difficult to realize. We introduce a dynamic framework in which programmed DC-biased space-time modulations of material parameters reproduce the response of otherwise readily accessible media.

The advancement of metamaterials reveals the potential of nanophotonics in applications across disciplines. We explored a new topology for photonic integrated circuits for the control of non-Hermicity, nonreciprocity, mathematical convolution, and hyperspectral image classification. The advanced electromagnetic engineering promises to fundamentally reshape the design concepts of system-on-chip technology.

Here, we report a rapid, single-shot interference lithography strategy for the fabrication of wafer-scale, highly ordered metallic nanogap arrays with nanoscale precision. The resulting structures exhibit uniform sub-10 nm gap features across centimeter scales, yielding dense plasmonic hotspots. To assess optical performance, the arrays were employed as surface-enhanced Raman spectroscopy (SERS) substrates using a self-assembled monolayer of biphenyl-4-thiol as a standard Raman reporter. The substrates demonstrate strong Raman enhancement, confirming efficient electromagnetic field localization and high device reliability, ideal for trace detection of chemicals via SERS and various vibrational spectroscopies.

Nanophotonic color routers suffer severe performance degradation under oblique illumination. We introduce Optical Structural Similarity (OSS), a constraint integrated into adjoint-based topology optimization to enforce geometric continuity between angle-specific unit cells. OSS significantly suppresses stitching errors, enabling angle-robust color routing across the entire image sensor.

We address two key problems in the coherent control of wave transport: the joint control of multiple observables and the probability distribution of random wave transport in arbitrary media.

We create disordered structures exhibiting specific spectral features, from stealthy hyperuniformity to completely new structures, “gyromorphs”, that exhibit rotational order alongside translational disorder. Using direct laser writing, we fabricate these structures as polymer nanolattices and report their optical properties in the near infrared range. Preliminary data suggests a photonic bandgap in gyromorphs on par with that of stealthy hyperuniformity in low refractive index material.

We introduce and experimentally validate an analog circuit emulator of Mie scattering. The emulator adopts a modular architecture: excitation conditions are specified by generators and filters, whereas distinct networks of resistors, capacitors, and inductors capture material dispersion and radiative properties.

We present nanoprinted diffractive neural networks fabricated by two-photon nanolithography and show their potential in the context of high-content and high-throughput classifiers for imaging flow cytometry. These optical neural networks perform high-speed classification of objects at visible wavelengths, highlighting the potential of integrated optofluidic machine-learning systems.

We demonstrate optically tunable edge detection by integrating a dielectric metasurface with multilayer 2D materials exhibiting strong photo-induced refractive index modulation. By applying an external pump laser, we dynamically switch the edge-detection functionality on and off. This approach provides a reconfigurable, all-optical platform for high-speed image processing.

We demonstrate a passive dispersion-engineered nonlocal metasurface for wavelength-selective spatial-frequency filtering, enabling low-pass circle detection with a tunable numerical aperture and high-pass edge detection. Experiments show up to 3-fold SNR enhancement for circles, clear edge enhancement and improved classification accuracy of objects using a single-layer convolutional neural network.

We will present a unified perspective on how deliberately tailored dispersion can be used to create absorbing layers (dielectric and magnetic) with unprecedented bandwidth-to-thickness ratios. We will further show how closely related ideas can enable compact, on-chip realizations of negative reactive behavior that are typically associated with active or stability-limited circuits.

In this study, we demonstrate that full time-reversal can be achieved in a spatially symmetric homogeneous medium by exploiting the unique wave-matter interactions in plasma temporal slabs. We show that, while conventional non-dispersive time-interfaces are constrained by a physical bound on the time reflection efficiency due to momentum conservation, a dispersive plasma medium allows breaking this limit by introducing mechanical momentum exchanges as a new degree of freedom. By utilizing a Lagrangian formalism, we reveal that, by preserving the inertia of carriers at a time-interface, rather than their time derivative, triggers a kickback effect that enables the time-reflected wave to exceed the time-transmitted wave, up to canceling time-transmission and fully reverting the wave without violating total momentum conservation. We validate our analytical predictions through a microwave experiment involving a time-varying metamaterial transmission line, where we successfully measure time-reflections greater than time-transmission. Our findings prove that mechanical momentum exchanges are an essential ingredient for achieving full time-reversal, offering new playgrounds for broadband phase conjugation and distortion compensation for applications in imaging and telecommunications.

we demonstrate a programmable chaotic cavity platform capable of realizing arbitrary frequency-agile nonreciprocal functionalities. Fixed magnetically self-biased ferrites inside the cavity provide intrinsic time-reversal symmetry breaking, while tunable reciprocal port terminations enable boundary programmability. As an example, a two-port isolator functionality is realized by optimizing the load reflection phases.Near-unity forward transmission and isolation exceeding 110 dB are achieved, with the possibility for continuous shift of the operating frequency in the relative spectral range of 15%. The proposed platform is capable of realizing reconfigurable, arbitrary passive nonreciprocal multiport devices.

Optical neural interfaces offer a promising avenue for monitoring and stimulating neuronal activity with high spatiotemporal resolution. This talk presents two highly integrated devices that combine optical metasurfaces with CMOS imaging technology for precise neuron localization. The first system, a "needle" device, enables the probing of deep brain neural circuits while significantly minimizing tissue displacement compared to the state of the art. The second system, a "surface" device as thin as a sheet of paper, can be conformally attached to the brain's surface and operated entirely wirelessly. Together, these technologies provide transformative, minimally invasive tools for mapping and interrogating complex neural circuitry in living and behaving animals.

Disordered metasurfaces offer unique properties unattainable with periodic or ordered metasurfaces, notably the absence of deterministic interference effects at specific wavelengths and angles. In this work, we introduce a lithography-free nanofabrication approach to realize cascaded disordered plasmonic metasurfaces with submicrometer total thickness. We experimentally characterize their angle-resolved specular and diffuse reflections using the bidirectional reflection distribution function and develop accurate theoretical models that remain valid even at large incidence angles. These models reveal the intricate interplay between coherent (specular) and incoherent (diffuse) scattering and demonstrate how coherent illumination can strongly influence the perceived color of diffusely scattered light. Exploiting this effect, we realize a centimeter-scale chromo-encryption device whose color changes depending on whether it is viewed under direct or diffuse illumination. Our results lay the groundwork for advanced nanophotonic platforms based on stacked disordered metasurfaces, offering versatile optical functionalities inaccessible with traditional multilayer thin-film technologies or single-layer metasurfaces.

We present successful realization of coherent virtual absorption in metasurfaces-based platforms. Our analysis and results provide new opportunities for engineered optical energy storage, optical memories, and sensing using metasurface-based designs.

Imaging science is a critical enabler of revolutionary scientific advances across disciplines. However, current imaging technologies face prohibitive trade-offs in resolution, penetration depth and experimental complexity. Here, we introduce new classes of micro- and nanostructured photonic surfaces which scale down and enhance light-matter interactions, to overcome existing challenges in imaging science in a miniaturized, on-chip format.

We present 3D topology optimization of manufacturable SERS substrates maximizing averaged Raman power from randomly oriented anisotropic molecules in elastic and inelastic scattering. A trace formulation gives closed-form SO(3) averaging and requires one pump plus few reciprocal emission solves. Length-scale constraints prevent singularities; Ag is broadband, Si3N4 narrower and Q-limited.

Optical metasurfaces enable flat, compact, and lightweight optical components through precise control of the phase and amplitude of scattered light. Among them, nonlocal metasurfaces employ guided mode resonances (GMRs) to achieve high-Q responses with enhanced light-matter interactions, yet most remain static after fabrication. Two-dimensional transition metal dichalcogenides (TMDs) offer a promising route toward active tunability. Here, we integrate monolayer WS2 with nonlocal metasurfaces to pursue strong exciton-photon coupling and dynamic control of GMRs. To efficiently design and optimize the metasurface geometry, we employ a deep neural network (DNN) surrogate model trained on RCWA simulation results. Fabricated nanogratings exhibit clear GMRs, establishing an experimentally validated platform for actively tunable hybrid excitonic-photonic systems with potential applications in dynamic wavefront shaping, augmented reality, and LiDAR systems.

In this contribution, we investigate twisted cascaded metasurfaces as an effective approach for vortex beam generation and rotation sensing. The key physical mechanism relies on stacking two phase-engineered metasurfaces and introducing a controllable relative rotation between them, which enables twist-dependent wavefront manipulation. In this way, an incident plane wave can be transformed into an electromagnetic vortex mode whose topological charge can be tuned through the twist angle. Furthermore, since the transmitted field can be engineered to exhibit a strong sensitivity to the relative angular displacement, the same principle can be exploited for rotation detection as well as for vortex mode identification.

Time varying dielectric metasurfaces supporting sharp optical resonances with a non trivial electromagnetic field distribution represent a unique platform for realizing temporal interfaces for metasurface guided waves. Rapidly changing metasurface resonance enables frequency conversion and temporal scattering of a concurrently propagating waves.We demonstrate that localized free carrier generation can be used to generate large, highly localized quasistatic magnetic fields inside the metasurfaces. The resulting nanoscale magnetization, supported by the residual circulating currents, persists after the departure of the time scattered waves. We further demonstrate that the initial electromagnetic energy of the injected waves is partitioned between the time reflected/refracted waves,residual motion of the free carriers, and a quasi-static magnetic field

In this work, we develop a reconfigurable infrared metasurface based on the phase-change material VO extsubscript{2}, whose optical response is dynamically controlled by temperature. By exploiting the insulator–metal transition of VO extsubscript{2}, we engineer the bianisotropic response of the metasurface and tailor the absorption mechanisms in its two crystalline states. We demonstrate temperature-dependent control of absorption asymmetry: in one phase, the structure exhibits a fully symmetric absorption profile, whereas in the other it displays pronounced asymmetry. The proposed concept is supported by comprehensive numerical simulations and validated through experimental fabrication and optical characterization.

We determine the minimal number of tunable parameters for coherent control of multichannel wave scattering systems by relating functionality constraints to the codimension, enabling routing, demultiplexing and other target functionalities.

Electric Propulsion is an emerging space technology enabling efficient, precise control of small satellite constellations. Miniaturizing thruster components is a key challenge. This work presents compact waveguides using a flexible, fully printed metasurface inside a cylindrical structure, achieving over 70% size reduction. Tunable metasurface elements can also enable active control of waveguide mode propagation and thruster operation.

This paper presents a programmable metamaterial based on printed circuit technology designed through a multi-condition inverse framework. The structure consists of a passive two-dimensional lattice operating at 10 GHz with a fixed internal element distribution. Multiple electromagnetic states are achieved via switch-controlled boundary conditions. Beam steering is demonstrated as a target functionality, where four distinct steering angles are enforced through prescribed power division and progressive phase constraints. The design is formulated as a constrained optimization problem and solved using an adjoint-based gradient method. The final configuration satisfies all steering states simultaneously without structural modification, demonstrating that boundary switching combined with inverse design enables programmable behavior in a fully passive PCB-compatible metamaterial platform.

The production of gyration, or non-reciprocal phase shifts, is a key enabler for a wide range of non-reciprocal devices. Specifically, gyrators are a universal building block for creating isolators, circulators, and other non-reciprocal transfer functions. In this presentation, we will discuss how gyration responses can be achieved using spatio-temporal modulation. Three distinct approaches will be described -- the use of electro-optic material properties to natively induce non-reciprocal rotation of light polarization, the use of electro-optic modulations on discrete resonators to break overall transfer function symmetry, and extending these principles to creating pure gyration with simultaneously symmetric amplitude responses. Our experimental implementations include both photonic integrated circuits and superconducting microwave systems.

We present a passive, single-layer, polarization-independent metasurface isolator operating in the microwave regime. The design is based on a meta-atom exhibiting D4h(C4v) symmetry, realized through the hybrid integration of permanent magnets and ferrites. This symmetry enables a pure moving-medium effect without the need for external biasing or time-varying modulation. The proposed metasurface achieves an isolation level of 37 dB at the operating frequency for both orthogonal polarizations.

We present a bias-free, ultrathin metasurface that delivers giant optical isolation without external magnets, temporal modulation, or strong nonlinearities. The design combines self-magnetized ferrite nanodisks in a stable vortex state with resonant enhancement of light–matter interaction using quasi-bound states in the continuum. The metasurface exhibits a pure synthetic moving-medium response at optical frequencies, yielding giant nonreciprocal directional dichroism.

In this work, we design and realize a compact, synchronization-based acoustic circulator for the transmission of time-varying information. We demonstrate strong non-reciprocity in both transmitted energy and information accuracy, with directional signal amplification attributed to the energy compensation from the synchronized limit cycle.

We study a metasurface formed by magnetically biased plasmonic cylinders supporting nonreciprocal magnetoplasmonic modes. Using a magnetized Drude model and cylindrical wave analysis, the electromagnetic response of the structure is investigated. The metasurface exhibits asymmetric dispersion and directional surface plasmon propagation, enabling tunable nonreciprocal behavior.

I will share our recent progress in development of large-scale manufacturing of dielectric metasurfaces using 12-inch wafer processing and their applications to passive and active flat optics-based devices, including wide field of view metalenses, RGB imaging cameras, 1-micron pixel liquid crystal on silicon meta-displays and more.
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Metasurfaces have been attracting tremendous attention from both the scientific community and industry in recent years. Due to their ability to efficiently control phase, amplitude and polarization of light at the nanoscale, they can be designed to perform a variety of optical functions and substitute conventional bulk optics with thinner flat optical components with enhanced functionality. However, to make their way to real products, the development of foundry-type large-scale manufacturing of metasurfaces with fixed PDKs is of primarily importance. In this talk, I will share our recent progress in development of large-scale manufacturing of dielectric metasurfaces using 12-inch wafer processing and their applications to passive and active flat optics-based devices, including wide field of view metalenses, RGB imaging cameras, 1-micron pixel liquid crystal on silicon meta-displays and more.

We demonstrate reversible and multi-state changes in mid-infrared (MIR) transmission of inorganic halide perovskites with opposite polarity under light and heat. This antithetical response results from a polaron-like lattice distortion under illumination (reducing transmission), and from the material’s negative thermo-optic coefficient combined with lattice expansion from heat (increasing transmission). Our results establish halide perovskites for reconfigurable photonic devices based on photostriction.

We numerically and experimentally investigate a metasurface-based platform to realize compact free-space optical cavities whose quality (Q) factors can be largely modulated by very small mechanical displacements, while keeping the overall device thickness smaller than ~20 μm. The device consists of Fabry-Perot-like cavities where one or both mirrors are replaced by resonant and strongly dispersive metasurfaces. The interplay between the strongly dispersive reflection spectra of the metasurface and the round-trip phase accumulated in the cavity leads to a much sharper dependence of the optical response of the overall device with respect to the cavity length. Experimentally, we demonstrated cavities where only one mirror is replaced by a metasurface, and that feature a fivefold modulation of Q as the cavity length is changed by less than 100 nm. Simulations suggest that the Q factor modulation can be up to 20x in devices with two resonant metasurfaces. We will discuss these results and prospect of this platform for reconfigurable linear and nonlinear photonics.

Dispersive time-varying metasurfaces promise unprecedented scattering phenomena, ranging from Floquet harmonic generation to parametric amplification. Here, we introduce a causal Floquet–Bloch formulation for the scattering analysis of metasurfaces with arbitrary dispersion under temporal modulation. The proposed approach enables efficient calculation of reflected and transmitted harmonics while respecting causality. As a proof of concept, we study a strongly dispersive WS$_2$ metasurface and demonstrate asymmetric harmonic scattering and signatures of parametric amplification under appropriate modulation conditions.

We demonstrate a reconfigurable nonlinear optical computing platform in which structured illumination writes a programmable nonlinear source in an unpatterned nonlinear thin film. A single-modulator, common-path architecture enables fast quadratic processing, including tunable focusing, vortex generation, log–polar mapping, and complex-valued kernels for feature extraction.

We present experimentally constructed optical eigenpulses, the extension of an operator theory produced by S.A.R. Horsley et al. into the optical wave regime. Tailoring a probing pulses to a material modulation eigenvalues enables evolution preserving light pulses with controllable efficiencies for use in cloaking, communications and filtering. Although the experiments explored are in the near infrared, the application to EM waves can be generalised to visible or telecom frequencies.

The geometric phase associated with an acoustic field is a key concept in topological acoustics. This concept arises from the geometric representation of a field as a vector in a multidimensional complex Hilbert space. The topological characteristics of acoustic waves are revealed as unconventional features in the manifold spanned by the multidimensional acoustic field state vector as it is parametrically rotated.

The globally distributed ambient seismic noise has been widely used to monitor near-Earth surface dynamic processes. This is made by reconstructing time-lapse signal response within the medium (i.e., empirical Green’s functions, EGF) between seismic sensors.

Acoustic devices such as circuits, sensors, and filters rely on materials with spatial patterns of elastic constants. These patterns must have sufficient contrast to confine and manipulate acoustic waves, and they underpin key wireless technologies such as cell phones.

A topological acoustic metamaterial comprised of coupled waveguides is used to control geometric phase. The phases in the metamaterial satisfy all of DiVincenzo’s criteria for quantum bits and are referred to as phase bits, or phi-bits.

We measured the transmission and reflection parameters of the composites containing magnetic microwire inclusions during the composite matrix polymerization. A remarkable change of the reflection and transmission in the range of 4-7 GHz upon the matrix polymerization is observed. The obtained results can be considered as a basis for a novel sensor technique for non-destructive and contactless monitoring of composites using ferromagnetic glass-coated microwires inclusions.

We provide our xperimental results on studies on effect of applied stress on Reflection coefficient (S22 parameter) of Co-rich glass-coated ferromagnetic amorphous microwire measured using free space microwave spectroscopy at 2.45 GHz. The experimentally observed stress dependence of the reflection coefficient allows for contactless stresses and damage monitoring of composites with such magnetic microwire inclusions

We demonstrate a near-field engineering approach to enhance the sensitivity of resonant metasurfaces through selective mode excitation and controlled modal coupling that allows redistribution of the electromagnetic field toward regions of stronger analyte interaction. This strategy enables improved sensing performance in both high- and low-Q resonant structures without relying solely on bandwidth narrowing. Our results show both numerically and experimentally that modal engineering of the near field provides a robust pathway to optimize sensitivity.

A surge of publications on space-time modulated metamaterials has appeared in recent years. Although related theories and experiments have been developed, methodologies connecting idealized models with realistic implementations remain limited. In this paper, we present a systematic workflow for the design and modeling of RF metamaterials under relatively high-frequency modulation.

We report a five- layer gold and polymer dispersed liquid crystal multilayer metamaterial exhibiting sub unity permittivity in the optical regime. Using spectroscopic ellipsometry and effective medium theory, we characterize this Epsilon near zero phenomenon. This architecture serves as a foundational platform for thermally switching the system towards hyperbolic dispersion.

Bandgap engineering in layered double perovskites is demonstrated through heterovalent cation alloying in Sn-alloyed (PEA)₄AgBiBr₈ microcrystals. Optical spectroscopy reveals a non-linear evolution of the bandgap with composition, highlighting the potential of lead-free layered perovskites as tunable platforms for photonic materials.

We present inverse-designed metasurface in- and out-couplers for optical see-through AR waveguides, optimized in the diffraction-order domain. The approach aligns RGB propagation, enables guided-power recycling, and preserves zeroth-order transmission of external light, suppressing parasitic diffraction while maintaining high see-through image quality.

We reveal hyperbolic surface phonon polaritons in non-hyperbolic YVO4 crystals and show that in-plane dispersion can be thermally reconfigured by varying the temperature. By using cryo-sSNOM, we directly visualized an in-situ dynamic control of topological transitions via modulation, expanding the operational spectral range and providing unprecedented control over polaritonic properties.

We demonstrate a topology-optimized hybrid photonic–plasmonic coupler combining a gold nanodisk with an inverse-designed SiN coupler, achieving strong Purcell-enhancement and nearly 80% waveguide coupling efficiency, enabling scalable integration of classical and quantum light sources.

Dispersion-engineered elastic metasurface on an aluminum plate enables broadband achromatic focusing of antisymmetric flexural waves through continuous thickness grading and coupling correction, enhancing confocal piezoelectric energy harvesting.

Put your abstractThis paper investigates the design of a two-dimensional underwater Luneburg lens based on circular meta-atoms. To realize the required refractive index profile, the relationship between the radius of the circular cylinders and the phase delay was numerically derived. While the initial design utilized rigid cylinders, it was observed that using solid steel cylinders—commonly used for actual fabrication—resulted in degraded focusing performance due to the reduction in impedance mismatch. To address this, the phase delay relationship was reevaluated considering the material properties of the solid cylinders. Numerical simulations verify that the modified design achieves significantly enhanced focusing performance compared to the initial solid model. here

Efficient solar thermophotovoltaic (STPV) systems require photonic structures that can tailor both solar absorption and thermal emission spectra. In this work, we study two structures, a metal-insulator-metal (MIM) design and a multilayer architecture, for use as absorbers and emitters in STPV systems. The study mainly focuses on spectral reshaping for broadband absorption and selective thermal emission. Simulation results show that both designs can modify the spectrum effectively, although with different spectral features and tuning behavior. The MIM structure offers flexible control of resonant features, while the multilayer design provides another practical route for selective spectral tailoring. This work provides a basis for the design and fabrication of solar absorbers and emitters for STPV device.

Reliable energy delivery remains a major challenge for implantable medical devices, particularly in applications requiring device miniaturization and long-term operation. Wireless power transfer (WPT) offers a promising alternative to battery-based solutions, but its performance is often limited by transmitter–receiver misalignment, separation distance, and strict size constraints on implanted components. In this work, we present a flexible metasurface-enhanced wireless power transfer system designed for biomedical implant applications. The proposed metasurface patch improves magnetic near-field coupling while maintaining mechanical flexibility. Experimental results demonstrate improved power transfer efficiency and robust performance under different curvature and separation conditions compared to a conventional two-coil configuration.

We present a rigorous electromagnetic model of a waveguide inside which a graphene sheet is contained. Rigorous dispersion equations for all mode families transverse electromagnetic (TEM), transverse electric (TE), and transverse magnetic (TM) are systematically derived from Maxwell’s equations with complete boundary conditions. We demonstrate that only the plasmonic TM0 mode satisfies the quantum Čerenkov condition at Thz regime.

The impact of the dielectric thickness composing a MS AMC is studied here. Although the dual PEC/PMC behavior is achieved with this design when observed in the far field, it is shown here that the spatial position of the field antinodes is not strictly on the surface of the MS when the latter is composed of a sufficiently thick dielectric substrate.

Silica-gold and silica-silver multishell spherial nanoresonators were tuned to achieve large near-field enhancement. Based on the optical cross-section and near-field characteristics of the individual multishells, the material of the metal shell was selected. Then, 3D passive and active periodic multishell-patterns were studied considering their optical response, near-field and effective optical properties. ENZ and ENP regions appear in the effective permittivity spectra of the inspected targets.

Nonlinear metasurfaces enable compact manipulation of light at the nanoscale. Here, we demonstrate dynamic control of second-harmonic chirality using a nonlocal lithium-niobate (LN) metasurface. By engineering metasurfaces on LN thin films, the SH polarization is continuously tuned from right- to left-handed circular states, enabling spin-decoupled second-harmonic holography.

This work presents a compact framework for evaluating and optimizing the feed efficiency of metasurface (MTS) antennas using a double-path wave arrangement. A circular metasurface aperture of radius $10lambda$ is designed at 29 GHz on a grounded dielectric substrate with relative permittivity $varepsilon_r = 6.3$ and thickness $h = 0.635$ mm, characterized by an average transparent reactance $X_0 = -300,Omega$. A triaxial feeding structure excites a radially propagating surface wave (SW), enabling separation of surface-wave, space-wave, and collected power contributions, as illustrated in Fig.~ ef{fig:powerflow_avg_reactance}. The optimized configuration achieves a feed efficiency of approximately 88\%, as shown in Fig.~ ef{fig:feed_eff}. By applying a tapered leakage profile, efficient conversion of the guided SW into leaky-wave radiation is obtained, resulting in a total radiation efficiency of about 70\% and a simulated gain of 35 dBi with dominant right-handed circular polarization, as confirmed by the far-field patterns in Fig.~1 ef{fig:radiation}. The results demonstrate that proper engineering of the average reactance and feed geometry enables highly efficient millimeter-wave metasurface antennas.

The ॐ-potential framework unifies sources and fields in anisotropic, non-reciprocal, and non-Hermitian media, extending electromagnetism to near-fields, linking hidden momentum, Beer-Lambert attenuation, photonic density of states, and structured-light formation within a single analytical foundation.

We explore a new strategy to seamlessly integrate the ferroelectric (FE) functionality of a twisted-hBN with a light-emitting semiconductor monolayer. The electrostatic potential on the surface of the twisted-hBN confines excitons in an adjacent MoSe2 monolayer or bilayer. Those excitons confined along the domain walls and reside atop the domains are spectrally separated due to the Stark shift induced by an in-plane electric field, strongest at the domain walls. They also exhibit drastically different diffusion and localization behavior, establishing an excitonic analogue of optical metasurfaces.

We present an objective-free approach to momentum-space imaging based on 3D-printed ellipsoidal microlenses integrated directly on semiconductor microcavities. Such microlens provides high numerical aperture (up to NA ≈ 0.95), enabling wide-angle collection and multiplexed, parallel mapping of dispersion relations from multiple spatial locations without a conventional microscope objective. The microlenses also enhance optical excitation, reducing the polariton condensation threshold by nearly an order of magnitude. This compact, cryo-compatible platform establishes a scalable route toward integrated and multiplexed momentum-space photonics.

We present the hyperbolic analog of a bullseye grating that allows simultaneous far-field coupling of all polaritonic states with in-plane hyperbolicity, leading to high coupling efficiency with strong spectral and angular selectivity.

We revisited light–matter interactions under relative motion, focusing on group-velocity matching between an emitter and electromagnetic modes supported by a medium. This condition gives rise to frozen modes - wavepackets stationary in the emitter frame - resulting in dramatic enhancements of the local density of optical states, and optomechanical forces.

In this contribution, we explore an adiabatic process mimicking time-reflection. Traditionally, generating strong time reflections required nearly instantaneous, high-amplitude modulations that are technically difficult to sustain. We propose a more practical alternative by demonstrating that efficient pulse reversal can be achieved through the moderate, adiabatic modulation of a plasmonic waveguide. By utilizing a plasmonic waveguide with tunable carrier concentrations, we show that a relatively slow adjustment of the plasma frequency facilitates temporal reflections driven by the reversal of group velocity rather than phase velocity. Although this specific regime does not time-reverse interference phenomena, we demonstrate that it successfully inverts the pulse’s temporal evolution and dispersion. Our theory further clarifies the impact of broken spatial symmetries on momentum evolution, providing a theoretical foundation for implementing exotic temporal scattering processes. Ultimately, by shifting toward adiabatic modulation, we enable sophisticated wave control within realistic optical frameworks, bypassing the stringent requirements of ultrafast material shifts.

We describe our lab’s Si-photonic “Very-large-scale Integrated high-Q Nanophotonic Pixels” (VINPix) for single-cell and single-molecule Raman scattering. First, we show how these resonators enable subcellular differentiation and functional state characterization of cells in the tumor immune microenvironment (TIME). Then, we show how these sensors can be used for peptide and glycoconjugate sequencing. We tether peptides from major histocompatibility complex to each resonator, and use dynamic Raman spectroscopy to monitor the cleavage of each amino acid from the distal terminus. We also show how these resonators, combined with computational metadynamics, can be used to identify previously unseen molecular species.

Modern biomedicine demands precise, local sources of reactive oxygen species (ROS) for therapies like photodynamic treatment, where excess radicals harm healthy tissues and insufficient yields limit efficacy. Here, we present light-sensitive metamaterials based on biocompatible vaterite spherulites as porous hosts uniformly loaded with silver nanoparticles (AgNPs), leveraging plasmonic enhancement for visible-light-driven ROS generation. The hybrid structure exploits localized surface plasmon resonance (LSPR) of AgNPs to shift absorption into the therapeutic window (400–700 nm), boosting electron transfer to oxygen under low-intensity irradiation, while the vaterite matrix ensures nanoparticle stability, uniform distribution, and controlled dosing without aggregation.

We demonstrate a planar silicon nanocavity that resolves weak dielectric perturbations from biological tissue sections. Subwavelength variations in refractive index and thickness are transduced into measurable resonance shifts and structural color contrast. The observed behavior is dictated by interference-induced modulation of effective optical thickness from tissue sections.

Continuous cardiovascular monitoring is essential for managing circulatory health and disease, yet most wearable sensors are constrained by reliance on electrical transduction and built-in electronics. We present a circuit-free, all-optical approach using diffraction from a skin-interfaced nanophotonic surface to detect minute skin strains from the arterial pulse. A smartphone camera records the shifting diffraction pattern in real time, removing the need for spectrometers or other optical hardware. In phantom and human studies, we recovered high-fidelity arterial pulse waves and detected benign arrhythmic events in close agreement with a clinical reference. Derived waveforms captured features linked to arterial stiffness, a key cardiovascular risk marker. Our approach uses battery-free, cost-effective, and disposable nanophotonic platforms enabling scalable monitoring for healthcare and broad consumer applications.

In this paper, microcrystalline cellulose is chemically treated to replace the C6 hydroxy group with one of higher polarizability leading to functionalized cellulose with tunable permittivity and ultimately affording graded-index organic metamaterials. Thin films are cast of several samples, each with a different functional group, and measured for their electrical permittivity. Quantum chemistry calculations are used to predict the outcome of the measurement with excellent accuracy.

The growing energy consumption of deep learning applications create a need for efficient neuromorphic hardware. First, I will present a framework for non-linear neuromorphic computing based on purely linear scattering, which is widely applicable across platforms. Second, I will discuss efficient physics-based training methods for classical and quantum neuromorphic systems.

This talk introduces a class of physical neural networks based on programmable transmission-line metamaterials (2D circuit networks). They consist of a grid of subwavelength unit cells with tunable reactive elements that serve as simple wave-based information processing nodes for learning and inference. Learned associations between input and output signals are stored in the reactive loading elements, and information processing is performed through wave propagation and interference across the grid.

Non-linearity is a pivotal ingredient to the universal approximation theorem for artificial neural networks, but implementing non-linear transformations in wave-based physical neural networks (WPNNs) is notoriously challenging. Recent work has explored the use of pro- grammable metasurfaces (PMs) in WPNNs to encode and non-linearly transform input data, while the learnable parameters were implemented in subsequent digital layers. In this work, we study a multilayer WPNN whose layers are PM-parametrized chaotic cavities. While the input data is encoded into the configuration of some PM elements, most PM elements are phys- ical learnable parameters. Non-linearity arises in our WPNN due to the encoding of input data into the configuration of PM elements and because mutual coupling between them results in a non-linear dependence of the transfer function on these PM elements’ configuration. Based on a full-wave simulation at 140 GHz of a compact chaotic cavity parametrized by a 100-element PM, we study the ability of our WPNN to approximate non-linear functions. Specifically, we examine the contribution of three factors to our WPNN’s expressivity: (i) the encoding function mapping input data to PM element characteristics, (ii) the mutual coupling strength between PM elements, and (iii) the number of WPNN layers.

We report a room-temperature mechanical platform that realizes logical elastic bits, namely classical qubit analogues encoded in the nonlinear spectrum of a two-mass oscillator joined by a conical spring. Large-amplitude excitation generates a stable ladder of harmonics with well-defined amplitudes and phases. By projecting the measured two-mass velocity field onto the in-phase and out-of-phase eigenvectors, we obtain complex coefficients that map directly onto a Bloch-sphere representation. Equal-frequency spectral pairings produce time-independent logical states suitable for phase-defined memory, whereas detuned harmonic pairings create deterministic Bloch-vector precession that enables passive gate-like rotations. Because multiple spectral blocks can be assigned to separate logical bits, one resonator can host several qubit analogues without additional hardware. The results establish a compact and experimentally accessible route toward quantum-inspired logic based on nonlinear mechanical vibrations.

I will present our latest progress on how we experimentally achieve new metasurface platforms for free-space and integrated photonics applications. Work includes the development of metaoptics using wafer-scale deep-UV fabrication on silicon and glass substrates, and programmable integrated circuits using complex metasurfaces using laser-written phase change material.

Conformal metasurfaces enable enhanced aberration control and wide field-of-view imaging but remain constrained by limited scalability and alignment precision in existing fabrication approaches. We present a wafer-scale thermoforming strategy that reshapes metasurface-embedded thermoplastic substrates into highly curved geometries with micron-level alignment accuracy on large-area platforms. A predictive thermorheological finite element model incorporating measured viscoelastic properties guides deformation-aware design, allowing pre-compensation of strain-induced phase errors and recovery of near-diffraction-limited performance. We demonstrate freestanding curved metalenses, conformal refractive–metasurface hybrid optics, and a wide field-of-view metalens compound eye. This work establishes thermoforming as a scalable and industrially compatible route to high-performance conformal photonic systems.

Wafer-scale sol–gel nanoimprint lithography enables phase-controlled TiO₂ metasurfaces (amorphous, anatase, and rutile) for high-efficiency, high-NA metalenses with diffraction-limited performance.

Metasurfaces manipulate light using subwavelength meta-atoms, enabling ultrathin optical components such as metalenses. However, conventional fabrication methods like EBL suffer from limited scalability and high cost. Here, we demonstrate two wafer-scale near-infrared metalenses fabricated by photolithography and nanoimprinting, achieving high-resolution imaging and presenting scalable, cost-effective pathways toward metalens mass production.

It is shown that dispersive and Bode-Fano tuning can be combined to significantly increase the antenna bandwidth over that of dispersive tuning or Bode-Fano tuning alone. Although these techniques to increase bandwidth are applied in the present paper to electrically small antennas, they could equally well be applied to increase the bandwidths of the unit-cell inclusions (metamolecules) in metamaterials.

This work presents an overview of the use of dielectric strip gratings for leaky-wave antenna (LWA) applications, including a comprehensive dispersion analysis of a grounded dielectric slab loaded with periodic dielectric strips. The study examines their potential for mode control and radiation pattern shaping, emphasizing the additional design flexibility enabled by dielectric corrugations, conformal surfaces, shaped strips and anisotropic materials. In particular, anisotropy is highlighted as a powerful parameter for dispersion engineering and enhanced polarization control. The presentation includes representative antenna design examples and a thorough characterization of the structure’s dispersive behavior.

Put your abstract hereThe contribution aims to show the evolution in the design of Radial Line Slot Arrays, from the local approach, where the slot length and positions are found using a periodic model, to the non-local approach, where the slots are stand-alone radiating elements that realize a non-smooth aperture current distribution, and back to a local approach for the brand-new metasurface version of an RLSA. The advantages and drawbacks of the different approaches will be highlighted.

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