Metasurfaces composed of spatially arranged ultrathin subwavelength elements are promising photonic devices for manipulating optical wavefronts,with potential applications in holography,metalens,and multiplexing com-munications.Finding microstructures that meet light modulation requirements is always a challenge in designing metasurfaces,where parameter sweep,gradient-based inverse design,and topology optimization are the most commonly used design methods in which the massive electromagnetic iterations require the design computational cost and are sometimes prohibitive.Herein,we propose a fast inverse design method that combines a physics-based neural network surrogate model(NNSM)with an optimization algorithm.The NNSM,which can generate an accurate electromagnetic response from the geometric topologies of the meta-atoms,is constructed for electro-magnetic iterations,and the optimization algorithm is used to search for the on-demand meta-atoms from the phase library established by the NNSM to realize an inverse design.This method addresses two important prob-lems in metasurface design:fast and accurate electromagnetic wave phase prediction and inverse design through a single phase-shift value.As a proof-of-concept,we designed an orbital angular momentum(de)multiplexer based on a phase-type metasurface,and 200 Gbit/s quadrature-phase shift-keying signals were successfully transmitted with a bit error rate approaching 1.67×10-6.Because the design is mainly based on an optimization algorithm,it can address the"one-to-many"inverse problem in other micro/nano devices such as integrated photonic circuits,waveguides,and nano-antennas.

International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology,Institute of Microscale Optoelectronics,Shenzhen University,Shenzhen 518060,China;College of New Materials and New Energies,Shenzhen Technology University,Shenzhen 518118,China;Guangdong Provincial Key Laboratory of Optical Information Materials and Technology and Institute of Electronic Paper Displays,South China Academy of Advanced Optoelectronics,South China Normal University,Guangzhou 510006,China

[1]GUOQING JING;PEIPEI WANG;HAISHENG WU;JIANJUN REN;ZHIQIANG XIE;JUNMIN LIU;HUAPENG YE;YING LI;DIANYUAN FAN;SHUQING CHEN-.Neural network-based surrogate model for inverse design of metasurfaces)[J].光子学研究（英文）,2022(06):1462-1471

NNSM

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