Dual-function photonic spin Hall effect sensor for high-precision refractive index sensing and graphene layer detection.

In this paper, a photonic spin Hall effect (PSHE) sensor for high-precision refractive index (RI) detection and graphene layer number detection is proposed. Numerical analysis is performed by the transfer matrix method. The graphene material is introduced into the layered topology to stimulate the generation of PSHE phenomenon, and both H polarization and V polarization displacements occur simultaneously. The effects of parameters such as chemical potential, relaxation time, and external temperature on the PSHE shift are also discussed. The displacement of H polarization can be used for RI detection, and the measurement range (MR), sensitivity (S), figure of merit (FOM), and detection limit (DL) are 1.1-1.5, 127.85 degrees/RIU, 2412, and 2.08×10-5, respectively. The superior sensing performance provides a theoretical possibility for the detection of solids, liquids, and gases. The shift characteristic of V polarization is appropriate for detecting the number of layers in graphene, with a MR and S of 1-9 layers and 4.54 degrees/layer. The impacts of dielectric loss on sensor performance are also considered. We hope that the proposed PSHE multifunctional sensor can improve a theoretical idea for novel sensor design.