@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{58606, author = {{Mathew, Albert and Aschwanden, Rebecca and Tripathi, Aditya and Jangid, Piyush and Sain, Basudeb and Zentgraf, Thomas and Kruk, Sergey}}, issn = {{1530-6984}}, journal = {{Nano Letters}}, keywords = {{metasurfaces, nanophotonics, nonreciprocity, optical isolators, silicon photonics}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Nonreciprocal Metasurfaces with Epsilon-Near-Zero Materials}}}, doi = {{10.1021/acs.nanolett.4c06188}}, year = {{2025}}, } @article{61255, abstract = {{Abstract Topological states have been widely investigated in different types of systems and lattices. In the present work, we report on topological edge states in double-wave (DW) chains, which can be described by a generalized Aubry-André-Harper (AAH) model. For the specific system of a driven-dissipative exciton polariton system we show that in such potential chains, different types of edge states can form. For resonant optical excitation, we further find that the optical nonlinearity leads to a multistability of different edge states. This includes topologically protected edge states evolved directly from individual linear eigenstates as well as additional edge states that originate from nonlinearity-induced localization of bulk states. Extending the system into two dimensions (2D) by stacking horizontal DW chains in the vertical direction, we also create 2D multi-wave lattices. In such 2D lattices multiple Su–Schrieffer–Heeger (SSH) chains appear along the vertical direction. The combination of DW chains in the horizonal and SSH chains in the vertical direction then results in the formation of higher-order topological insulator corner states. Multistable corner states emerge in the nonlinear regime.}}, author = {{Schneider, Tobias and Gao, Wenlong and Zentgraf, Thomas and Schumacher, Stefan and Ma, Xuekai}}, issn = {{2192-8614}}, journal = {{Nanophotonics}}, number = {{4}}, pages = {{509--518}}, publisher = {{Walter de Gruyter GmbH}}, title = {{{Topological edge and corner states in coupled wave lattices in nonlinear polariton condensates}}}, doi = {{10.1515/nanoph-2023-0556}}, volume = {{13}}, year = {{2024}}, } @article{49607, abstract = {{In this work, we utilize thin dielectric meta-atoms placed on a silver substrate to efficiently enhance and manipulate the third-harmonic generation. We theoretically and experimentally reveal that when the structural symmetry of the meta-atom is incompatible with the lattice symmetry of an array, some generalized nonlinear geometric phases appear, which offers new possibilities for harmonic generation control beyond the accessible symmetries governed by the selection rule. The underlying mechanism is attributed to the modified rotation of the effective principal axis of a dense meta-atom array, where the strong coupling among the units gives rise to a generalized linear geometric phase modulation of the pump light. Therefore, nonlinear geometric phases carried by third-harmonic emissions are the natural result of the wave-mixing process among the modes excited at the fundamental frequency. This mechanism further points out a new strategy to predict the nonlinear geometric phases delivered by the nanostructures according to their linear responses. Our design is simple and efficient and offers alternatives for the nonlinear meta-devices that are capable of flexible photon generation and manipulation.}}, author = {{Liu, Bingyi and Geromel, René and Su, Zhaoxian and Guo, Kai and Wang, Yongtian and Guo, Zhongyi and Huang, Lingling and Zentgraf, Thomas}}, issn = {{2330-4022}}, journal = {{ACS Photonics}}, keywords = {{Electrical and Electronic Engineering, Atomic and Molecular Physics, and Optics, Biotechnology, Electronic, Optical and Magnetic Materials}}, number = {{12}}, pages = {{4357--4366}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Nonlinear Dielectric Geometric-Phase Metasurface with Simultaneous Structure and Lattice Symmetry Design}}}, doi = {{10.1021/acsphotonics.3c01163}}, volume = {{10}}, year = {{2023}}, } @article{44044, abstract = {{Dispersion is present in every optical setup and is often an undesired effect, especially in nonlinear-optical experiments where ultrashort laser pulses are needed. Typically, bulky pulse compressors consisting of gratings or prisms are used to address this issue by precompensating the dispersion of the optical components. However, these devices are only able to compensate for a part of the dispersion (second-order dispersion). Here, we present a compact pulse-shaping device that uses plasmonic metasurfaces to apply an arbitrarily designed spectral phase delay allowing for a full dispersion control. Furthermore, with specific phase encodings, this device can be used to temporally reshape the incident laser pulses into more complex pulse forms such as a double pulse. We verify the performance of our device by using an SHG-FROG measurement setup together with a retrieval algorithm to extract the dispersion that our device applies to an incident laser pulse.}}, author = {{Geromel, René and Georgi, Philip and Protte, Maximilian and Lei, Shiwei and Bartley, Tim and Huang, Lingling and Zentgraf, Thomas}}, issn = {{1530-6984}}, journal = {{Nano Letters}}, keywords = {{Mechanical Engineering, Condensed Matter Physics, General Materials Science, General Chemistry, Bioengineering}}, number = {{8}}, pages = {{3196 -- 3201}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Compact Metasurface-Based Optical Pulse-Shaping Device}}}, doi = {{10.1021/acs.nanolett.2c04980}}, volume = {{23}}, year = {{2023}}, } @inproceedings{46485, abstract = {{We present a miniaturized pulse shaping device that creates an arbitrary dispersion through the interaction of multiple metasurfaces on less than 2 mm3 volume. For this, a metalens and a grating-metasurface between two silver mirrors are fabricated. The grating contains further phase information to achieve the device's pulse shaping functionality.}}, author = {{Geromel, René and Georgi, Philip and Protte, Maximilian and Bartley, Tim and Huang, Lingling and Zentgraf, Thomas}}, booktitle = {{CLEO: Fundamental Science 2023}}, location = {{San Jose, USA}}, publisher = {{Optica Publishing Group}}, title = {{{Dispersion control with integrated plasmonic metasurfaces}}}, doi = {{10.1364/cleo_fs.2023.fth4d.3}}, year = {{2023}}, } @inbook{47543, author = {{Zentgraf, Thomas and Sain, Basudeb and Zhang, Shuang}}, booktitle = {{Fundamentals and Applications of Nonlinear Nanophotonics}}, editor = {{Panoiu, Nicoae C.}}, isbn = {{978-0-323-90614-2}}, publisher = {{Elsevier}}, title = {{{Symmetry governed nonlinear selection rules in nanophotonics }}}, doi = {{10.1016/B978-0-323-90614-2.00011-0}}, year = {{2023}}, } @article{40513, abstract = {{Geometric-phase dielectric meta-lenses made of silicon with high numerical aperture and short focal lengths are fabricated and characterised. For circularly polarised light, the same meta-lens can act as a converging or diverging lens, depending on the handedness of the circular polarisation. This effect enables application for optical tweezers that trap or release µm-size polymer beads floating in a microfluidic channel on demand. An electrically addressable polarisation converter based on liquid crystals may be used to switch between the two states of polarisation, at which the light transmitted through the meta-lens is focused (trapping) or defocussed (releasing), respectively.}}, author = {{Geromel, René and Rennerich, Roman and Zentgraf, Thomas and Kitzerow, Heinz-Siegfried}}, journal = {{Liquid Crystals}}, number = {{7-10}}, pages = {{1193--1203}}, publisher = {{Taylor & Francis}}, title = {{{Geometric-phase metalens to be used for tunable optical tweezers in microfluidics}}}, doi = {{10.1080/02678292.2023.2171146}}, volume = {{50}}, year = {{2023}}, } @inproceedings{46484, abstract = {{Efficient third-harmonic generation control is theoretically studied. Dielectric nanostructures placed on the metallic substrate could offer effective geometric-phase modulation on third-harmonic signals by selecting proper structure rotational symmetry.}}, author = {{Liu, Bingyi and Huang, Lingling and Zentgraf, Thomas}}, booktitle = {{Conference on Lasers and Electro-Optics}}, location = {{San Jose, USA}}, publisher = {{Optica Publishing Group}}, title = {{{Efficient Third-harmonic Generation Control with Ultrathin Dielectric Geometric-phase Metasurface}}}, doi = {{10.1364/cleo_qels.2022.fth1a.7}}, year = {{2022}}, } @article{32088, abstract = {{Subwavelength dielectric resonators assembled into metasurfaces have become a versatile tool for miniaturizing optical components approaching the nanoscale. An important class of metasurface functionalities is associated with asymmetry in both the generation and transmission of light with respect to reversals of the positions of emitters and receivers. The nonlinear light–matter interaction in metasurfaces offers a promising pathway towards miniaturization of the asymmetric control of light. Here we demonstrate asymmetric parametric generation of light in nonlinear metasurfaces. We assemble dissimilar nonlinear dielectric resonators into translucent metasurfaces that produce images in the visible spectral range on being illuminated by infrared radiation. By design, the metasurfaces produce different and completely independent images for the reversed direction of illumination, that is, when the positions of the infrared emitter and the visible light receiver are exchanged. Nonlinearity-enabled asymmetric control of light by subwavelength resonators paves the way towards novel nanophotonic components via dense integration of large quantities of nonlinear resonators into compact metasurface designs.}}, author = {{Kruk, Sergey S. and Wang, Lei and Sain, Basudeb and Dong, Zhaogang and Yang, Joel and Zentgraf, Thomas and Kivshar, Yuri}}, issn = {{1749-4885}}, journal = {{Nature Photonics}}, keywords = {{Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials}}, pages = {{561–565}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{Asymmetric parametric generation of images with nonlinear dielectric metasurfaces}}}, doi = {{10.1038/s41566-022-01018-7}}, volume = {{16}}, year = {{2022}}, }