Highly sensitive and stable identification of graphene layers via the topological edge states and graphene regulation to enhance the photonic spin Hall effect

Abstract

The detection of graphene layers is of great significance for the research and development of graphene materials. However, the multilayer accurate detection technology has yet to be improved. The photonic spin Hall effect (PSHE) is an effective tool to characterize the variation of graphene nanostructural parameters. In this work, graphene layer number detection is proposed, which is based on topological edge states and graphene modulation to enhance the PSHE. Utilizing the generation of topological edge states, the PSHE is enhanced at a specific frequency point f = 198.493 GHz and possesses topological protection. The results show that in combination with graphene modulation and surface electric field localization, the PSHE can be enhanced again at f = 198.493 GHz. Compared with the method based on the surface plasmon resonance and optical tunneling effect, the PSHE displacement is enhanced up to 5222.03 times the wavelength λ, which is significantly improved by two orders of magnitude. By locking the PSHE peak, the theoretically highly sensitive and stable detection of 1–25 graphene layers is achieved with a sensitivity of 1.401 × 10⁻² m nm⁻¹, expanding the thickness variation of graphene layers at the nanometer level by 10⁷ times to the centimeter level and with a linear fitting reliability of 0.999. This work proposes a novel approach to enhance the PSHE, enabling high-precision electromagnetic detection, which is anticipated to facilitate advancements in fundamental research, production, and processing of graphene and nanotechnology products.