Dielectric Meta-Reflectarray for Broadband Linear Polarization Conversion and Optical Vortex Generation

TLDR

Plasmonic metasurfaces can abruptly change light phase for subwavelength control, but most designs rely on metallic resonators that suffer low coupling efficiency and ohmic loss. We aim to replace metallic resonators with high‑refractive‑index silicon cut‑wires and a silver ground plane to create a dielectric meta‑reflectarray. The design employs silicon cut‑wires on a silver ground plane to provide broadband phase manipulation. Experimentally, the device achieves >98 % linear polarization conversion over a 200 nm bandwidth and generates high‑efficiency optical vortex beams from 1500–1600 nm, demonstrating the potential of dielectric resonators for ultra‑efficient metasurfaces.

Abstract

Plasmonic metasurfaces have recently attracted much attention due to their ability to abruptly change the phase of light, allowing subwavelength optical elements for polarization and wavefront control. However, most previously demonstrated metasurface designs suffer from low coupling efficiency and are based on metallic resonators, leading to ohmic loss. Here, we present an alternative approach to plasmonic metasurfaces by replacing the metallic resonators with high-refractive-index silicon cut-wires in combination with a silver ground plane. We experimentally demonstrate that this meta-reflectarray can be used to realize linear polarization conversion with more than 98% conversion efficiency over a 200 nm bandwidth in the short-wavelength infrared band. We also demonstrate optical vortex beam generation using a meta-reflectarray with an azimuthally varied phase profile. The vortex beam generation is shown to have high efficiency over a wavelength range from 1500 to 1600 nm. The use of dielectric resonators in place of their plasmonic counterparts could pave the way for ultraefficient metasurface-based devices at high frequencies.