Enhanced and tunable photonic spin Hall effect in metasurface bilayers

Abstract

We study theoretically the photonic spin Hall effect (PSHE) in metasurface bilayers with twisted adjacent two-dimensional material layers. When the coupling strength between adjacent twisted metasurfaces is strong, it can be found that the giant PSHE shifts of the reflected and transmitted beams exist at different types of topological transition points. For weakly coupling strength between metasurfaces, the PSHE shifts of reflected and transmitted beams present oscillations due to the Fabry–Perot resonance in metasurface bilayers. PSHE shifts can be manipulated by controlling physical parameters such as the twist angle of metasurface bilayers and the voltage applied to metasurfaces. By combining with the weak measurement method, these phenomena can be expected to provide a promising observation platform for investigating moire physics and twistronics in photonics.