Cascaded metasurfaces for high-purity vortex generation

Feng Mei; Geyang Qu; Xinbo Sha; Jing Han; Moxin Yu; Hao Li; Qinmiao Chen; Ziheng Ji; Jincheng Ni; Cheng-Wei Qiu; Qinghai Song; Yuri Kivshar; Shumin Xiao

doi:10.1038/s41467-023-42137-1

Cascaded metasurfaces for high-purity vortex generation

Nat Commun. 2023 Oct 12;14(1):6410. doi: 10.1038/s41467-023-42137-1.

Authors

Feng Mei^#¹, Geyang Qu^#², Xinbo Sha¹, Jing Han¹, Moxin Yu¹, Hao Li¹, Qinmiao Chen¹, Ziheng Ji¹, Jincheng Ni³, Cheng-Wei Qiu³, Qinghai Song^{4

5}, Yuri Kivshar^{6

7}, Shumin Xiao^{8

9

10}

Affiliations

¹ Ministry of Industry and Information Technology Key Lab of Micro-Nano Optoelectronic Information System, Harbin Institute of Technology Shenzhen, 518055, Shenzhen, P. R. China.
² Pengcheng Laboratory, 518055, Shenzhen, Guangdong, P. R. China.
³ Department of Electrical and Computer Engineering, National University of Singapore, 117583, Singapore, Singapore.
⁴ Ministry of Industry and Information Technology Key Lab of Micro-Nano Optoelectronic Information System, Harbin Institute of Technology Shenzhen, 518055, Shenzhen, P. R. China. qinghai.song@hit.edu.cn.
⁵ Pengcheng Laboratory, 518055, Shenzhen, Guangdong, P. R. China. qinghai.song@hit.edu.cn.
⁶ Nonlinear Physics Center, Research School of Physics, Australian National University, Canberra, ACT2601, Australia. yuri.kivshar@anu.edu.au.
⁷ Qingdao Innovation and Development Center, Harbin Engineering University, 266000, Qingdao, Shandong, P. R. China. yuri.kivshar@anu.edu.au.
⁸ Ministry of Industry and Information Technology Key Lab of Micro-Nano Optoelectronic Information System, Harbin Institute of Technology Shenzhen, 518055, Shenzhen, P. R. China. shumin.xiao@hit.edu.cn.
⁹ Pengcheng Laboratory, 518055, Shenzhen, Guangdong, P. R. China. shumin.xiao@hit.edu.cn.
¹⁰ Collaborative Innovation Center of Extreme Optics, Shanxi University, 030006, Taiyuan, Shanxi, P.R. China. shumin.xiao@hit.edu.cn.

^# Contributed equally.

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.