Highly efficient spin-polarized beam splitter based on silicon Pancharatnam–Berry metasurface

Abstract

Abstract The spin-polarized conversion and splitting of beam are highly important for photonic researches and applications. Although the photonic spin Hall effect (PSHE) realized by the Pancharatnam–Berry (PB) metasurface has shown unprecedented capabilities to control spin-polarized light, spin-polarized beam splitting metadevices suffer from the limitations of low-efficiency. Here, we present a highly efficient spin-polarized beam splitter (SPBS) based on PB metasurface comprising silicon nano elliptical cylinder (Si-NEC) arrays. Because of the electromagnetic multipole resonance inside the designed Si-NECs, the PB metasurface can achieve high transmittance and enhanced PSHE. Therefore, the SPBS based on the PB metasurface can achieve a high spin conversion efficiency of nearly 100%, while ensuring a transmittance of 87% at 622 nm wavelength. It can also maintain a good working effect within the bandwidth of 600–660 nm. Furthermore, by introducing spatial shift between the two reverse Si-NEC arrays, the SPBS can also be used to realize 45° polarization rotation of an incident linearly polarized light, avoiding the input polarization angle dependence. Our design may have potential applications in high-performance and broadband spin-photonic devices.