Spin Hall effect of transmitted light for graphene–silica aerogel photonic crystal in terahertz region

Abstract Photonic spin Hall effect (SHE) holds great potential applications for the development of spin-based nanophotonic devices. Due to the weak spin–orbit interaction, it is highly desirable to tune and enhance the photonic SHE. However, such a goal remains elusive, especially for the transmitted light. Here, we present the significant enhancement of SHE behavior for transmitted light in terahertz region by introducing the graphene monolayers into adjacent silica aerogel layers of photonic crystal. The spin shift is quite sensitive to the period number and Fermi energy of graphene layers. We find that the value of spin shift is mainly decided by the phase of Fresnel transmission coefficients. In addition, two different tuned regions have been revealed: one is the low frequency region in which the significant feature is the giant spin shift over broad angle and frequency ranges, and the other is the high frequency region where the spin shift can be gradually enhanced as the period number increases. These findings pave the way to achieve the enhanced SHE for transmitted light in terahertz region and may open the possibility for manipulating the photonic SHE.