@article{63827, abstract = {{Light-emitting diodes (LEDs) are becoming increasingly important across various sectors of the lighting industry and are being used more frequently. In the field of symbolic projection, research is increasingly focusing on implementing light modulation using energy-efficient, incoherent LEDs rather than lasers. Since light modulation in micro- and nano-optics is typically achieved through phase modulation, Finite-Difference Time-Domain (FDTD) simulations are employed for analysis. The objective of this article is to investigate different approaches for approximating incoherent monochromatic light sources within FDTD simulations. To this end, two approaches based on dipole sources are considered, as well as a method involving plane waves with modulated wavefronts based on Cosine–Fourier functions and a method based on the superposition of Gaussian beams. These methods are evaluated in terms of their accuracy using a two-dimensional double-slit configuration and are compared against a fully incoherent analytical reference.}}, author = {{Metzner, Dominik and Potthoff, Jens and Zentgraf, Thomas and Förstner, Jens}}, issn = {{2304-6732}}, journal = {{Photonics}}, keywords = {{tet_topic_opticalantenna, tet_topic_numerics, tet_topic_meta}}, number = {{2}}, publisher = {{MDPI AG}}, title = {{{Approximating Incoherent Monochromatic Light Sources in FDTD Simulations}}}, doi = {{10.3390/photonics13020128}}, volume = {{13}}, year = {{2026}}, } @article{64873, abstract = {{Continuous flow catalysis utilizing gel-bound organocatalysts within a microfluidic reactor represents a compelling strategy in the realm of organic synthesis. In this study, a quinuclidine-based catalytic monomer (QMA) was synthesized to create polymer gel dots through the process of photopolymerization that serve as a support for the catalyst. The resulting gel-bound organocatalysts were assembled within a continuous microfluidic reactor to facilitate the Baylis–Hillman reaction between various aldehydes and acrylonitrile at a temperature of 50 °C. The conversion of the product was assessed using 1H NMR spectroscopy as an offline analytical method over a duration of 8 h. The findings indicated that highly reactive aldehydes achieved conversion rates exceeding 90%, in contrast to their less reactive counterparts. Furthermore, these results were juxtaposed with previously published data derived from alternative synthetic methodologies, revealing that the continuous microfluidic reactions employing integrated organocatalysts within polymer networks exhibited significantly higher conversions with reduced reaction times (8 h) at the same temperature (50 °C). Additionally, the influence of different geometries (round, triangular, and square) of the gel dots on catalytic activity was investigated, with round and square gel dots demonstrating slightly superior performance compared with triangular gel dots, attributed to their increased surface area. Moreover, an extended reaction period of 6 days was conducted using 4-bromobenzaldehyde and acrylonitrile, resulting in a conversion rate exceeding 70%, which remained stable for 5 days before experiencing a slight decline due to product accumulation on the gel dots.}}, author = {{Killi, Naresh and Kumar, Amit and Nebhani, Leena and Obst, Franziska and Richter, Andreas and Reineke Matsudo, Bernhard and Zentgraf, Thomas and Kuckling, Dirk}}, issn = {{2470-1343}}, journal = {{ACS Omega}}, number = {{9}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Integrating an Organocatalyst into a Polymeric Gel Framework for the Continuous Microflow Baylis–Hillman Reaction}}}, doi = {{10.1021/acsomega.5c09476}}, volume = {{11}}, year = {{2026}}, } @article{61523, abstract = {{AbstractMetasurface holography offers a powerful approach for manipulating wavefronts at the nano and micro scale. Extensive research has been conducted to enhance the multiplexing capacity for diverse wavefronts. However, the independence of multiplexed channels is fundamentally restricted in techniques using single‐layer metasurfaces, resulting in unavoidable crosstalk and the need for post‐filtering of the output wavefronts. Here, a universal wavefront multiplexing concept is presented based on non‐injective transformation. By employing joint optimization on two metasurfaces, different channels can be independently designed without any constraints on the output wavefronts. To validate this approach, ultra‐compact orbital angular momentum (OAM) sorters are designed. In these experiments, the output beams from different channels can be independently mapped to 2D positions with high fineness. In another application of wavefront‐multiplexed holography, 10‐channel multiplexing is experimentally achieved with minimal crosstalk and without the need for post‐processing. These results demonstrate the independence between channels enabled by the non‐injective transformation in the method. The precise wavefront control and high multiplexing capacity underscore its potential for scalable wavefront manipulation devices.}}, author = {{Jin, Xiao and Zentgraf, Thomas}}, issn = {{0935-9648}}, journal = {{Advanced Materials}}, publisher = {{Wiley}}, title = {{{Independent Wavefront Multiplexing with Metasurfaces via Non‐Injective Transformation}}}, doi = {{10.1002/adma.202511823}}, volume = {{38}}, year = {{2026}}, } @article{63531, author = {{Doshi, Siddharth and Güsken, Nicholas Alexander and Dijk, Gerwin and Carlström, Johan and Ortiz-Cárdenas, Jennifer E. and Suzuki, Peter and Li, Bohan and Fordyce, Polly M. and Salleo, Alberto and Melosh, Nicholas A. and Brongersma, Mark L.}}, issn = {{0028-0836}}, journal = {{Nature}}, number = {{8096}}, pages = {{345--352}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Soft photonic skins with dynamic texture and colour control}}}, doi = {{10.1038/s41586-025-09948-2}}, volume = {{649}}, year = {{2026}}, } @article{64877, author = {{Taheri, Behnood and Kopylov, Denis and Hammer, Manfred and Meier, Torsten and Förstner, Jens and Sharapova, Polina R.}}, journal = {{arXiv}}, title = {{{Gain-induced spectral non-degeneracy in type-II parametric down-conversion}}}, doi = {{10.48550/ARXIV.2603.01656}}, year = {{2026}}, } @article{64978, abstract = {{The degrees of freedom (DoFs) of light determine the maximum number of independent signal channels an optical system can support. However, the polarization DoF is intrinsically limited to two by orthogonality, which causes unavoidable crosstalk and often forces position multiplexing, where different channels are assigned to distinct spatial locations to suppress crosstalk. This research introduces a multilayer synchronous polarization projection method that fundamentally increases the DoF for polarization multiplexing. The DoF equals twice the number of projection layers. We experimentally demonstrate six- channel polarization multiplexing holography without position multiplexing. The six-channel multiplexing results indicate that our approach exceeds the conventional polarization multiplexing method, yielding an average 3.79 dB improvement in extinction ratio across the six channels. Compared with the theoretical limit of traditional polarization multiplexing, our method reduces crosstalk by an average of 6.52 dB across all channels in a seven-channel design. The polarization projection method breaks the DoF limitation of polarization multiplexing, opening a path toward high-dimensional photonic information encoding for communication, encryption, and imaging.}}, author = {{Jin, Xiao and Zentgraf, Thomas}}, issn = {{2577-5421}}, journal = {{Advanced Photonics}}, number = {{02}}, publisher = {{SPIE-Intl Soc Optical Eng}}, title = {{{Increasing the design degree of freedom for polarization through multilayer synchronous polarization projection}}}, doi = {{10.1117/1.ap.8.2.026010}}, volume = {{8}}, year = {{2026}}, } @inproceedings{65357, author = {{Kim, Minjun and Devaraj, Vasanthan and Seo, Hyeon-Seok and Eom, Seongjae and Lee, Jeong-Su and Lee, Donghan and Zentgraf, Thomas and Lee, Jong-Min and Jeon, Min Yong}}, booktitle = {{Quantum Sensing and Nano Electronics and Photonics XXII}}, editor = {{Razeghi, Manijeh and Khodaparast, Giti A. and Vitiello, Miriam S.}}, publisher = {{SPIE}}, title = {{{Fabrication of uniform, high-field-enhanced plasmonic satellite clusters using multidewetting}}}, doi = {{10.1117/12.3095416}}, year = {{2026}}, } @article{65460, abstract = {{Beamsplitters represent fundamental components in both classical and quantum optical systems, enabling the distribution of light, as well as the generation of interference, superposition, and entanglement. However, optical networks constructed from conventional bulk 2 × 2-beamsplitters encounter inherent scalability issues, as the number of required beamsplitters scales quadratically with the number of optical modes for a fully connected network. Metasurfaces offer a promising route to overcome these constraints. By manipulating light at the wavelength scale, compact optical components with advanced functionalities can be constructed, which address several modes simultaneously. In this work, we design and experimentally utilize a metasurface as a multiport beamsplitter. Furthermore, we realized a multimode interferometer composed of two cascaded metasurfaces. We characterize the individual and cascaded metasurfaces by using classical light, showing controllable splitting ratios through tunable phase relations. We then expand the approach to quantum light, employing single photons to demonstrate second- and third-order photon correlations as well as single photon interference across multiple spatial paths. These results establish metasurface-based multiport beamsplitters as a scalable and reconfigurable platform bridging classical and quantum photonics. }}, author = {{Aschwanden, Rebecca and Claro-Rodríguez, Nicolás and Zhao, Ruizhe and Kallert, Patricia Anna Maria and Krieger, Tobias and Buchinger, Quirin and Covre da Silva, Saimon F. and Stroj, Sandra and Rota, Michele and Höfling, Sven and Huber-Loyola, Tobias and Rastelli, Armando and Trotta, Rinaldo and Huang, Lingling and Bartley, Tim and Jöns, Klaus and Zentgraf, Thomas}}, issn = {{2330-4022}}, journal = {{ACS Photonics}}, keywords = {{metasurface, beamsplitter, interferometer, quantum network, single photons, nanophotonics}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Cascaded Metasurface Interferometer for Multipath Interference with Classical and Quantum Light}}}, doi = {{10.1021/acsphotonics.6c00096}}, year = {{2026}}, } @article{65316, abstract = {{Metasurfaces are powerful tools for manipulating light using small structures on the nanoscale. In most metasurfaces, near-field couplings are treated as being unfavorable perturbations. Here, we experimentally investigate a structure consisting of sinusoidally modulated silicon waveguides where near-field coupling of local resonances leads to negative coupling, i.e., a negative coupling constant. This gives rise to wave-vector-dependent eigenstates of elliptical, linear, and circular polarizations. In particular, fully circular polarization states are not only present at a single point in momentum space (k-space) but also along a line. This circular polarization line, as well as a linear polarization line, emanates from a polarization degeneracy at the Dirac point. We experimentally validate the existence of these eigenstates and demonstrate the energy-, polarization-, and wave vector dependence of this metasurface as well as its sensitivity to fabrication tolerances. By tuning the incident k-vector, certain polarization-energy eigenstates are strongly reflected, allowing for uses in angle-tunable polarization filters and light sources.}}, author = {{Wetter, Helene and Wingenbach, Jan and Rehberg, Falk and Gao, Wenlong and Schumacher, Stefan and Zentgraf, Thomas}}, issn = {{2330-4022}}, journal = {{ACS Photonics}}, keywords = {{metasurface, waveguides, Dirac point, polarization, negative coupling}}, pages = {{2128--2133}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Polarization- and Wave-Vector Selective Optical Metasurface with Near-Field Coupling}}}, doi = {{10.1021/acsphotonics.5c02865}}, volume = {{13}}, year = {{2026}}, } @article{65655, abstract = {{A functionalization-free plasmonic nanogap platform enables reliable on-site SERS based oxidation-state differentiation of arsenic through uniform metal-vacuum-metal cavities with high electromagnetic enhancement and minimal background interference.}}, author = {{Kim, Minjun and Heo, Damun and Cho, Sung Yoon and Lee, Ye-Won and Gu, Sun-Hwa and Adhikari, Samir and Lee, Donghan and Jeong, Seok Soon and Kim, Hyuck Soo and Devaraj, Vasanthan and Zentgraf, Thomas and Jeon, Min Yong and Lee, Jong-Min}}, issn = {{2040-3364}}, journal = {{Nanoscale}}, number = {{8}}, pages = {{4292--4299}}, publisher = {{Royal Society of Chemistry (RSC)}}, title = {{{A functionalization-free plasmonic hole-sphere nanogap SERS platform for reliable on-site analysis and oxide-state classification}}}, doi = {{10.1039/d5nr03414k}}, volume = {{18}}, year = {{2026}}, } @inproceedings{65906, author = {{Jin, Xiao and Zentgraf, Thomas}}, booktitle = {{Metamaterials XV}}, editor = {{MacDonald, Kevin F. and Zayats, Anatoly V. and Staude, Isabelle}}, location = {{Strasbourg, France}}, publisher = {{SPIE}}, title = {{{OAM-multiplexed holography via cascaded metasurfaces without post sampling and position multiplexing}}}, doi = {{10.1117/12.3096579}}, volume = {{14075}}, year = {{2026}}, } @article{66555, abstract = {{Scalable plasmonic technologies face a critical trade‐off: few‐body architectures offer high enhancement but are sensitive to fabrication flaws, while scalable methods like solid‐state dewetting yield large, low‐enhancement gaps. We introduce a paradigm shift using a many‐body plasmonic architecture inspired by statistical mechanics. By moving toward the continuum limit, local geometric variations are statistically averaged out, effectively decoupling optical performance from microscopic disorder. We implement this concept via a lithography‐ and etching‐free, multi‐step dewetting strategy, creating wafer‐scale nanoclusters. This process strategically forms a robust many‐body system by introducing numerous small satellite nanoparticles between larger particles. Crucially, this design achieves a high collective enhancement that surpasses even optimized few‐body systems, despite having larger individual gaps. Under optimized conditions, these substrates exhibit a surface‐enhanced Raman scattering enhancement factor approaching 4 × 10^8 with unprecedented reproducibility (RSD of ∼10%). This scalable, low‐cost concept establishes a practical route toward reproducible wafer‐scale nanophotonic platforms for sensing, spectroscopy, and quantum technologies.}}, author = {{Kim, Minjun and Devaraj, Vasanthan and Seo, Hyeon‐Seok and Eom, Seong‐Jae and Lee, Jeong‐Su and Lee, Donghan and Jeon, Min Yong and Zentgraf, Thomas and Lee, Jong‐Min}}, issn = {{1863-8880}}, journal = {{Laser & Photonics Reviews}}, publisher = {{Wiley}}, title = {{{Engineering Disordered Many‐Particle Plasmonic Nanoclusters for Wafer‐Scale Uniform and Giant Electromagnetic Field Enhancement}}}, doi = {{10.1002/lpor.71610}}, year = {{2026}}, } @article{66632, abstract = {{Three‐dimensional (3D) assemblies of gold nanoparticles (AuNPs) offer a rich platform for plasmonic coupling and near‐field engineering, yet their optical behavior is often complex due to structural disorder and fabrication‐induced variability. Here, we present a systematic optical investigation of large‐scale 3D AuNP assemblies fabricated via meniscus‐guided assembly, focusing on the reproducibility, spatial uniformity, and mode evolution of their plasmonic responses. Spatially‐resolved dark‐field scattering measurements reveal that high‐aspect‐ratio AuNP pillars exhibit uniform scattering spectra along their height and across different pillars, despite variations in geometry and structure. Electromagnetic simulations suggest that this robustness arises from a collective many‐particle plasmonic response that remains optically active despite structural perturbations. The corresponding near‐field and surface‐charge distributions remain spatially distributed under representative structural perturbations, consistent with volumetric averaging across the three‐dimensional assembly. Building on this robust platform, we introduce compositional modulation through a core–satellite architecture by incorporating smaller AuNPs. This yields a composition‐dependent spectral redistribution, including the emergence of an additional long‐wavelength spectral feature in the core–satellite assemblies. Wavelength‐dependent surface‐enhanced Raman scattering measurements reveal contrasting responses under 633 and 785 nm excitation, reflecting redistribution of local plasmonic coupling pathways. These results provide process‐enabled guidelines for using meniscus‐guided 3D‐nanoprinting to realize robust nanoparticle assemblies.}}, author = {{Devaraj, Vasanthan and Kwak, Sunghyun and Kim, Hyeongjip and Sung, Sang‐Keun and Lee, Jong‐Min and Zentgraf, Thomas and Kim, Won‐Geun}}, issn = {{1863-8880}}, journal = {{Laser & Photonics Reviews}}, publisher = {{Wiley}}, title = {{{Spatially Uniform and Defect‐Tolerant Plasmonic Responses in 3D Printed Gold Nanoparticle Assemblies}}}, doi = {{10.1002/lpor.71686}}, year = {{2026}}, } @article{66744, author = {{Farheen, Henna and Chen, Yuheng and Chen, Peigang and Maan, Pranshu and Peana, Samuel and Senichev, Alexander and Shalaev, Vladimir M. and Boltasseva, Alexandra and Förstner, Jens and Kildishev, Alexander V.}}, issn = {{1077-260X}}, journal = {{IEEE Journal of Selected Topics in Quantum Electronics}}, keywords = {{tet_topic_opticalantenna}}, pages = {{1--12}}, publisher = {{Institute of Electrical and Electronics Engineers (IEEE)}}, title = {{{Efficient Silicon Nitride Quantum Interconnect for Intrinsic Silicon Nitride Single-Photon Emitters}}}, doi = {{10.1109/jstqe.2026.3722063}}, year = {{2026}}, } @article{66746, abstract = {{Several recent proposals in integrated photonics concern components that operate on so-called semi-guided waves. Given a dielectric multilayer slab structure, these are wave solutions that propagate along the slab with the functional dependence of ordinary harmonic plane waves, but with modal confinement in the direction perpendicular to the slab plane. While the in-plane unbounded waves are valid as a theoretical construct, practical devices will have to work with laterally confined optical fields. To that end we consider Gaussian superpositions of semi-guided waves, for a range of in-plane propagation angles, here named “semi-guided Gaussian beams.” This paper collects a series of relations that characterize these wave bundles, with emphasis on their divergence. The expressions resemble standard results for optical Gaussian beams, with modifications originating from the 1-D guiding and 1-D bundling. Examples for a high-contrast silicon-on-insulator slab at a typical telecom wavelength are discussed.}}, author = {{Hammer, Manfred and Förstner, Jens}}, issn = {{0740-3224}}, journal = {{Journal of the Optical Society of America B}}, keywords = {{tet_topic_waveguide}}, number = {{9}}, publisher = {{Optica Publishing Group}}, title = {{{Semi-guided Gaussian beams}}}, doi = {{10.1364/josab.606932}}, volume = {{43}}, year = {{2026}}, } @article{66870, abstract = {{Janus metasurfaces have attracted considerable attention in encrypted communication, imaging, and display due to their unusual bidirectional asymmetric optical manipulation characteristics. Particularly, their multifunctionalization is of great significance for enhancing the compactness and integration of optical systems. However, the realization of multifunctional Janus metasurfaces in the optical band still faces enormous difficulties and challenges, which are essentially limited by the anti-error design and processing methods of multi-layer cascade metasurfaces. Here, a triple-layer Janus metasurface based on cascaded plasmonic nano-antenna arrays fully buried in SiO2 is constructed. Among them, the cascaded plasma nano-antenna consists of two types of enantiomers for each wavelength. Each enantiomer is fabricated with two layers of L-shaped nanostructures with phase modulation and one layer of dimer nanostructures with polarization selection stacked alternately along the optical axis. We experimentally show that the Janus metasurface achieves bidirectional asymmetric multi-channel holographic encryption, simultaneously using propagation direction, phase, polarization, and wavelength for the first time in the near-infrared band, which is expected to provide a frontier route for multifunctional optical displays, high-level optical information encryption, and large-capacity full-duplex communication.}}, author = {{Wang, Guocui and Geromel, René and Wei, Qunshuo and Zhao, Ruizhe and Li, Xiaowei and Zentgraf, Thomas and Huang, Lingling}}, issn = {{2577-5421}}, journal = {{Advanced Photonics}}, number = {{05}}, pages = {{1--11}}, publisher = {{SPIE-Intl Soc Optical Eng}}, title = {{{Asymmetric multi-channel holography by cascaded plasmonic Janus metasurfaces}}}, doi = {{10.1117/1.ap.8.5.056006}}, volume = {{8}}, year = {{2026}}, } @inproceedings{60022, author = {{Brauckmann, Michael and Narvaez Castaneda, Emmanuel and Siebert, Dustin and Brecht, Benjamin and Förstner, Jens and Zentgraf, Thomas}}, booktitle = {{Proceedings of The 15th International Conference on Metamaterials, Photonic Crystals and Plasmonics}}, location = {{Malaga, Spain}}, title = {{{Enhancement Of Light-matter Interaction In Topological Waveguides And Resonators}}}, year = {{2025}}, } @article{61245, author = {{Barkhausen, Franziska and Ares Santos, Laura and Schumacher, Stefan and Sperling, Jan}}, issn = {{2469-9926}}, journal = {{Physical Review A}}, number = {{3}}, publisher = {{American Physical Society (APS)}}, title = {{{Entanglement between dependent degrees of freedom: Quasiparticle correlations}}}, doi = {{10.1103/physreva.111.032404}}, volume = {{111}}, year = {{2025}}, } @article{61246, abstract = {{Abstract The time-dependent one-dimensional nonlinear Schrödinger equation (NLSE) is solved numerically by a hybrid pseudospectral-variational quantum algorithm that connects a pseudospectral step for the Hamiltonian term with a variational step for the nonlinear term. The Hamiltonian term is treated as an integrating factor by forward and backward Fourier transforms, which are here carried out classically. This split allows us to avoid higher-order time integration schemes, to apply a first-order explicit time stepping for the remaining nonlinear NLSE term in a variational algorithm block, and thus to avoid numerical instabilities. We demonstrate that the analytical solution is reproduced with a small root mean square error for a long time interval over which a nonlinear soliton propagates significantly forward in space while keeping its shape. We analyze the accuracy and complexity of the quantum algorithm, the expressibility of the ansatz circuit and compare it with classical approaches. Furthermore, we investigate the influence of algorithm parameters on the accuracy of the results, including the temporal step width and the depth of the quantum circuit.}}, author = {{Köcher, Nikolas and Rose, Hendrik and Bharadwaj, Sachin S. and Schumacher, Jörg and Schumacher, Stefan}}, issn = {{2045-2322}}, journal = {{Scientific Reports}}, number = {{1}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Numerical solution of nonlinear Schrödinger equation by a hybrid pseudospectral-variational quantum algorithm}}}, doi = {{10.1038/s41598-025-05660-3}}, volume = {{15}}, year = {{2025}}, } @article{61249, author = {{Ai, Qiang and Wingenbach, Jan and Yang, Xinmiao and Wei, Jing and Hatzopoulos, Zaharias and Savvidis, Pavlos G. and Schumacher, Stefan and Ma, Xuekai and Gao, Tingge}}, issn = {{2331-7019}}, journal = {{Physical Review Applied}}, number = {{2}}, publisher = {{American Physical Society (APS)}}, title = {{{Optically and remotely controlling localization of exciton-polariton condensates in a potential lattice}}}, doi = {{10.1103/physrevapplied.23.024029}}, volume = {{23}}, year = {{2025}}, }