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Douglas H. Werner

Publications and source records attributed to Douglas H. Werner.

At least 19 recordsLinked to original sources

A Comprehensive Review of Large Language Models for Nanophotonics: From Surrogate Modeling to Autonomous Design

Metasurfaces have revolutionized the development of photonic devices by enabling unprecedented precision in light manipulation. However, their design processes are often constrained by computationally expensive simulations and complex high-dimensional design spaces. Although deep learning has accelerated the design process by serving as a surrogate model, it remains constrained by task-specific architectures and lacks universal reasoning capabilities. This review surveys how Large Language Models (LLMs) are adding semantic interfaces, code generation, and tool orchestration to established numerical nanophotonic workflows. We first outline the development from classical neural networks to transformer-based models and their applications in nanophotonic design. We then review the emergence of LLM-related methods in nanophotonics and organize them into two operational modes: surrogate models that treat structure-spectrum mapping as a language task, and agentic systems that have been demonstrated to generate code, orchestrate selected simulation steps, and support closed-loop optimization. Furthermore, to identify future cross-disciplinary opportunities, we briefly explore applications of LLMs in research fields such as materials science and wireless communications. This review concludes by looking ahead to the next generation of multimodal foundation models with physical perception capabilities. In this vision, artificial intelligence is evolving from passive tools into active collaborators, participating in autonomous scientific discovery.

physics.optics↗

Spatio-temporal coherent molding and retrieval of pulsed signals in optical waveguides

Optical waveguides are key elements for high fidelity, long distance optical communications. Coupled waveguide arrays allow for higher information density, steerting the propagation direction, and for encoding information. However, due to the mixing of relative phases for short pulses containing multiple waveguide-mode frequencies, a process for retrieving an encoded input state once these signals undergo coherent propagation remains elusive. A concept is presented to extract with high fidelity the phase-encrypted input signal from spatio-temporal propagated states. As a realization, an array of coupled waveguides is suggested with the retrieval mechanism being realized by local phase shifts that comply with the identified retrieval concept. Three dimensional full-wave electromagnetic simulations for broadband optical signals in coupled dielectric waveguides confirm the validity of the scheme and the high fidelity of information retrieval pointing to potential applications, for instance in ultrafast coherent coding and decoding of information imprinted on pulse sequences.

physics.optics↗

Towards a universal meta-optics solver via large language models

Metasurface design increasingly requires fast models that can operate across structurally distinct device families, rather than retraining a separate surrogate for every geometry class. Conventional neural network surrogates often depend on fixed-dimensional descriptors, family-specific output formats, and repeated architecture tuning, which limits their scalability across heterogeneous meta-atoms. Here, we present a unified large language model (LLM) workflow for multi-family metasurface modeling and inverse-design. Geometries, design parameters, and optical response channels were converted into a shared instruction-following text format and used to fine-tune Gemma-2-9B across 8 metasurface families. Compared with single-family baselines, the joint model simultaneously predicted the optical responses of all metasurface families while reducing the MSE for each family by an average of 56.5%. The same representation was also used for inverse design. These results show that a shared sequence-based LLM interface can provide a practical route to cross-family metasurface design while reducing the need for task-specific surrogate architectures.

physics.optics↗

Space-Time Modulated vs 2-Bit Reflect-Arrays: A Comparison of Main Beam Gain and Sidelobe Level Performance

This paper presents a comprehensive analysis of the phase errors introduced by 2-bit reflectarray architectures and investigates their impact on aperture synthesis for beam-steering applications. Building upon this analysis, an amplitude-aware synthesis technique based on space-time modulated (STM) reflect-arrays is proposed to mitigate the main-beam gain degradation commonly associated with STM-based equivalent phase generation while preserving the enhanced phase resolution enabled by temporal coding. A 10λby 10λ reflect-array aperture with λ/2 inter-element spacing is considered, where the desired aperture phase distribution is synthesized using a library of achievable reflection coefficients generated from all possible combinations of four 2-bit phase states distributed across (L) temporal segments. The proposed approach introduces a phase-tolerance window and selects the reflection state with the highest reflectance within the allowable phase range. By exploiting the inherent amplitude diversity of the STM state space, the proposed approach maximizes aperture efficiency while maintaining the desired beam-steering phase distribution. Numerical results demonstrate that the method substantially reduces the gain penalty typically associated with STM reflect-arrays along with providing significant sidelobe suppression.

physics.app-ph↗

Taming Randomness in Random Lasers: Programmable Disorder for Active Control of Random Lasing via Electric-Field-Directed Assembly of Nanowires

Random lasing exploits multiple scattering to provide optical feedback without conventional resonant cavities, enabling simplified architectures that are readily integrated into compact photonic platforms such as wearable sensors and lab-on-chip devices. However, the same disorder that enables cavity-free lasing also makes it challenging to control and tune the emission properties. Here, an electrically reconfigurable random-lasing platform based on dielectrophoretic assembly of chaining silver nanowires suspended in a dye gain medium is reported. An applied electric field across patterned quadrupole electrodes induces nanowire chaining and programmable alignment, enabling real-time reconfiguration of the disorder landscape. Based on the electrically driven disorder state transitions, tunable random-lasing characteristics, including reduced lasing thresholds, modulation of emission intensity, and control of the polarization state have been demonstrated. Simulations further indicate that chaining enhances scattering relative to absorption, providing more efficient radiative feedback, and the orientation of the nanowire network governs the polarization dependence of the system. These results establish a route to actively modulate random lasing through controllable disorder and point toward adaptive, reconfigurable photonic light sources and sensing systems.

physics.optics↗

Chat to Chip: Large Language Model Based Design of Arbitrarily Shaped Metasurfaces

Traditional metasurface design is limited by the computational cost of full-wave simulations, preventing thorough exploration of complex configurations. Data-driven approaches have emerged as a solution to this bottleneck, replacing costly simulations with rapid neural network evaluations and enabling near-instant design for meta-atoms. Despite advances, implementing a new optical function still requires building and training a task-specific network, along with exhaustive searches for suitable architectures and hyperparameters. Pre-trained large language models (LLMs), by contrast, sidestep this laborious process with a simple fine-tuning technique. However, applying LLMs to the design of nanophotonic devices, particularly for arbitrarily shaped metasurfaces, is still in its early stages; as such tasks often require graphical networks. Here, we show that an LLM, fed with descriptive inputs of arbitrarily shaped metasurface geometries, can learn the physical relationships needed for spectral prediction and inverse design. We further benchmarked a range of open-weight LLMs and identified relationships between accuracy and model size at the billion-parameter level. We demonstrated that 1-D token-wise LLMs provide a practical tool to designing 2-D arbitrarily shaped metasurfaces. Linking natural-language interaction to electromagnetic modelling, this "chat-to-chip" workflow represents a step toward more user-friendly data-driven nanophotonics.

physics.optics↗

Photonics of topological magnetic textures

Topological textures in magnetically ordered materials are important case studies for fundamental research with promising applications in data science. They can also serve as photonic elements to mold electromagnetic fields endowing them with features inherent to the spin order, as demonstrated analytically and numerically in this work. A self-consistent theory is developed for the interaction of spatially structured electromagnetic fields with non-collinear, topologically non-trivial spin textures. A tractable numerical method is designed and implemented for the calculation of the formed magnetic/photonic textures in the entire simulation space. Numerical illustrations are presented for scattering from point-like singularities, i.e. Bloch points, in the magnetization vector fields, evidencing that the geometry and topology of the magnetic order results in photonic fields that embody orbital angular momentum, chirality as well as magnetoelectric densities. Features of the scattered fields can serve as a fingerprint for the underlying magnetic texture and its dynamics. The findings point to the potential of topological magnetic textures as a route to molding photonic fields.

cond-mat.other↗

Data driven approaches in nanophotonics: A review of AI-enabled metadevices

Data-driven approaches have revolutionized the design and optimization of photonic metadevices by harnessing advanced artificial intelligence methodologies. This review takes a model-centric perspective that synthesizes emerging design strategies and delineates how traditional trial-and-error and computationally intensive electromagnetic simulations are being supplanted by deep learning frameworks that efficiently navigate expansive design spaces. We discuss artificial intelligence implementation in several metamaterial design aspects from high-degree-of-freedom design to large language model-assisted design. By addressing challenges such as transformer model implementation, fabrication limitations, and intricate mutual coupling effects, these AI-enabled strategies not only streamline the forward modeling process but also offer robust pathways for the realization of multifunctional and fabrication-friendly nanophotonic devices. This review further highlights emerging opportunities and persistent challenges, setting the stage for next-generation strategies in nanophotonic engineering.

physics.optics↗

Fixed-Attention Mechanism for Deep-Learning-Assisted Design of High-Degree-of-Freedom 3D Metamaterials

The traditional design approaches for high-degree-of-freedom metamaterials have been computationally intensive and, in many cases, even intractable due to the vast design space. In this work, we introduce a novel fixed-attention mechanism into a deep learning framework to address the computational challenges of metamaterial design. We consider a 3D plasmonic structure composed of gold nanorods characterized by geometric parameters and demonstrate that a Long Short-Term Memory network with a fixed-attention mechanism can improve the prediction accuracy by 48.09% compared to networks without attention. Additionally, we successfully apply this framework for the inverse design of plasmonic metamaterials. Our approach significantly reduces computational costs, opening the door for efficient real-time optimization of complex nanostructures.

physics.optics↗

Heterogeneous Freeform Metasurfaces: A Platform for Advanced Broadband Dispersion Engineering

Metasurfaces, with their ability to control electromagnetic waves, hold immense potential in optical device design, especially for applications requiring precise control over dispersion. This work introduces an approach to dispersion engineering using heterogeneous freeform metasurfaces, which overcomes the limitations of conventional metasurfaces that often suffer from poor transmission, narrow bandwidth, and restricted polarization responses. By transitioning from single-layer, canonical meta-atoms to bilayer architectures with non-intuitive geometries, our design decouples intrinsic material properties (refractive index and group index), enabling independent engineering of phase and group delays as well as higher-order dispersion properties, while achieving high-efficiency under arbitrary polarization states. We implement a two-stage multi-objective optimization process to generate libraries of meta-atoms, which are then utilized for the rapid design of dispersion-engineered metasurfaces. Additionally, we present a bilayer metasurface stacking technique, paving the way for the realization of high-performance, dispersion-engineered optical devices. Our approach is validated through the demonstration of metasurfaces exhibiting superior chromatic aberration correction and broadband performance, with over 81% averaged efficiency across the 420-nm visible-to-near-infrared bandwidth. Our synergistic combination of advanced design physics, powerful freeform optimization methods, and bi-layer nanofabrication techniques represents a significant breakthrough compared to the state-of-the-art while opening new possibilities for broadband metasurface applications.

physics.app-ph↗

Chiral Ball and Its Omnidirectional Circularly-Polarized Radiation

Chiral structures have reported radiation of circular polarized electromagnetic waves (CPs) in a specific direction. Here we report a class of torus knot radiators that is not only chiral but also three-dimensional (3-D) rotational symmetric along X, Y and Z axes. Because of this exotic chirality and symmetry, the knot radiator presented is able to demonstrate omnidirectional circular polarized radiation, which has never been reported in any known structures.

physics.class-ph↗

Contact tracing Inspired Efficient Computation by Energy Tracing

Inspired by the epidemic contact tracing technique, we propose a method to efficiently solve electromagnetics by tracing the energy distribution. The computational domain is adaptively decomposed, and the available computational resources are focused on those energy-active (infections) and their adjacent (exposed) domains, while avoiding the unnecessary computation of energy-null (unexposed) domains. As an example, we employ this method to solve several optics problems. The proposed method shows high efficiency while maintaining a good accuracy. The energy tracing method is based on the causality principle, and therefore is potentially transformative into other computational physics and associated algorithms.

cs.CE↗

System response analysis in wavenumber domain for linear space-invariant time-varying problems

Being a powerful tool for linear time-invariant (LTI) systems, system response analysis can also be applied to the so-called linear space-invariant (LSI) but time-varying systems, which is a dual of the conventional LTI problems. In this paper, we propose a system response analysis method for LSI problems by conducting Fourier transform of the field distribution on the space instead of time coordinate. Specifically, input and output signals can be expressed in the wavenumber (spatial frequency) domain. In this way, the system function in wavenumber domain can also be obtained for LSI systems. Given an arbitrary input and temporal profile of the medium, the output can be easily predicted using the system function. Moreover, for a complex temporal system, the proposed method allows for decomposing it into multiple simpler subsystems that appear in sequence in time. The system function of the whole system can be efficiently calculated by multiplying those of the individual subsystems.

physics.optics↗

Fundamental asymmetries between spatial and temporal boundaries in electromagnetics

Time-varying materials bring an extra degree of design freedom compared to their conventional time-invariant counterparts. However, few discussions have focused on the underlying physical difference between spatial and temporal boundaries. In this letter, we thoroughly investigate those differences from the perspective of conservation laws. By doing so, the building blocks of optics and electromagnetics such as the reflection law, Snell's law, and Fresnel's equations can be analogously derived in a temporal context, but with completely different interpretations. Furthermore, we study the unique features of temporal boundaries, such as their nonconformance to energy conservation and causality.

physics.optics↗

Evidencing non-Bloch dynamics in temporal topolectrical circuits

One of the core concepts from the non-Hermitian skin effect is the extended complex wavevectors (CW) in the generalized Brillouin zone (GBZ), while the origin of CW remains elusive, and further experimental demonstration of GBZ is still lacking. We show that the bulk states of an open quantum system dynamically governed by the Lindblad master equation exhibit non-Bloch evolution which results in CW. Experimentally, we present temporal topolectrical circuits to serve as simulators for the dynamics of an open system. By reconstructing the correspondence between the bulk states of an open system and circuit voltage modes through gauge scale potentials in the circuit, the non-Bloch evolution is demonstrated. Facilitated by the simulators and proper approach to characterize the non-Bloch band proposed here, the GBZ is confirmed. Our work may advance the investigation of the dissipative topological modes and provide a versatile platform for exploring the unique evolution and topology for both closed and open systems.

cond-mat.mtrl-sci↗

Chiral Balls: Knotted Structures with Both Chirality and Three-dimensional Rotational Symmetry

Knots have been put forward to explain various physical phenomena because of their topological stability. Nevertheless, few works have reported on the exotic symmetry properties that certain knots possess. Here we reveal an exceptional form of symmetry for a family of knots that are both chiral and three-dimensional (3-D) rotationally symmetric about every axis of a standard Cartesian coordinate system. We call these unique knotted structures chiral balls. To demonstrate the unprecedented physical characteristics exhibited by these unique structures, we study the electromagnetic scattering properties of a representative conductive chiral ball. In particular, a characteristic mode analysis is performed to investigate the intrinsic scattering properties of this chiral ball. With both chirality and 3-D rotational symmetry, the chiral ball is shown to exhibit an extraordinary isotropic circularly polarized scattering property, which has not been previously reported for any known electromagnetic structures. Because of their unique properties, chiral balls are expected to not only have a profound impact on the fields of electromagnetics and optics but also far beyond.

physics.class-ph↗

A Knotted Meta-molecule with 2-D Isotropic Optical Activity Rotating the Incident Polarization by 90°

Optical activity is the ability of chiral materials to rotate linearly-polarized (LP) electromagnetic waves. Because of their intrinsic asymmetry, traditional chiral molecules usually lack isotropic performance, or at best only possess a weak form of chirality. Here we introduce a knotted chiral meta-molecule that exhibits optical activity corresponding to a 90° polarization rotation of the incident waves. More importantly, arising from the continuous multi-fold rotational symmetry of the chiral torus knot structure, the observed polarization rotation behavior is found to be independent of how the incident wave is polarized. In other words, the proposed chiral knot structure possesses two-dimensional (2-D) isotropic optical activity as illustrated in Fig. 1, which has been experimentally validated in the microwave spectrum. The proposed chiral torus knot represents the most optically active meta-molecule reported to date that is intrinsically isotropic to the incident polarization.

physics.class-ph↗