Generation and conversion of a dual-band Laguerre-Gaussian beam with different OAM based on a bilayer metasurface

In this paper, we propose a bilayer metasurface with dual-operating modes to realize the generation and conversion of dual-band Laguerre-Gaussian beam with different OAM. The bilayer metasurface consists of amorphous silicon (a-Si) and amorphous antimony selenide (a-Sb2Se3). In transmission mode, the metasurface can transtbrm incident left-handed circularly polarized (LCP) Gaussian beam into one LCP Laguerre-Gaussian beam carrying topological charge l=-2 and one right-handed circularly polarized (RCP) Laguerre-Gaussian beam carrying topological charge l=-1, which enabled OAM modes multiplexing. In reflection mode, the metasurface can convert an incident LCP Gaussian beam into a LCP Laguerre-Gaussian beam carrying a topological charge l=-3 owing to the a-Sb2Se3 nanopillar that acts as a half-wave plate with high reflectivity. In addition, the OAM conversion between two arbitrary modes can be realized by the proposed metasurface. This work provides a valid method for OAM multiplexing and conversion, which holds a great applications value in high-speed optical communication systems. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

This paper proposes a bilayer metasurface with dual-operating modes for the generation and conversion of dual-band Laguerre-Gaussian beams with different orbital angular momentum (OAM). The metasurface can multiplex OAM modes in transmission mode and convert OAM in reflection mode. This work provides a valid method for OAM multiplexing and conversion, which has significant applications in high-speed optical communication systems.