Design of a graphene-based chiral trifunctional tunable terahertz metasurface

Abstract

Driven by the pressing demand for integration and miniaturization within the terahertz (THz) spectrum, this research introduces an innovative approach to construct chiral structures using dichroism as the target function. This initiative aims to tackle the prevalent issues of single-functionality, narrow application scope, and intricate design in conventional metasurfaces. The proposed multifunctional tunable metasurface employs a graphene-metal hybrid structure to address the critical constraints found in existing designs. When circularly polarized light is incident, the metasurface exhibits broadband circular dichroism (CD) function, generating CD intensities greater than 0.5 at 3.44–6.0 THz, and polarization switching function at 3.43–6.17 THz. When linearly polarized light is incident, the proposed design exhibits a broadband linear dichroism (LD) function, producing LD intensities greater than 0.5 at 2.25–5.65 THz and a polarization conversion function at 3.32–6.05 THz. Its broad bandwidth ensures that each function is competitive and effective. A noteworthy feature is the capability to adjust the graphene's chemical potential and the state of the incident light to finely calibrate the intensity of each functional aspect. This innovation makes the proposed multifunctional metasurface a significant reference for the development of chiral photodetectors, CD supermirrors, smart switches, and polarization digital imaging systems within the THz range.