Cascaded metasurfaces for high-purity vortex generation

作者：Feng Mei, Geyang Qu, Xinbo Sha, Jing Han, Moxin Yu, Hao Li, Qinmiao Chen, Ziheng Ji, Jincheng Ni, Cheng‐Wei Qiu, Qinghai Song, Yuri S. Kivshar, Shumin Xiao · 发表于：Nature Communications · 年份：2023 · DOI：10.1038/s41467-023-42137-1 · 被引用次数：122 · 研究领域：Orbital Angular Momentum in Optics、Metamaterials and Metasurfaces Applications、Plasmonic and Surface Plasmon Research

Abstract We introduce a new paradigm for generating high-purity vortex beams with metasurfaces. By applying optical neural networks to a system of cascaded phase-only metasurfaces, we demonstrate the efficient generation of high-quality Laguerre-Gaussian (LG) vortex modes. Our approach is based on two metasurfaces where one metasurface redistributes the intensity profile of light in accord with Rayleigh-Sommerfeld diffraction rules, and then the second metasurface matches the required phases for the vortex beams. Consequently, we generate high-purity LG p,l optical modes with record-high Laguerre polynomial orders p = 10 and l = 200, and with the purity in p , l and relative conversion efficiency as 96.71%, 85.47%, and 70.48%, respectively. Our engineered cascaded metasurfaces suppress greatly the backward reflection with a ratio exceeding −17 dB. Such higher-order optical vortices with multiple orthogonal states can revolutionize next-generation optical information processing.