Universal Analytical Modeling of Terahertz Graphene Metasurfaces

Abstract

Control over the optical response of graphene metasurfaces enables many promising applications in terahertz devices, including beam filters, polarizers, and absorbers. In this paper, we provide an analytical theory that enables us to use equivalent circuit models to simulate these responses. Closed-form expressions are provided for their associated scattering spectra, including an infinity of parallel R-L-C circuits for each metasurface morphology, which are calculated and tabulated once and for all. These models' accuracy is verified by comparing their results with those that are derived from full-wave simulations. Moreover, applications of these models are presented to anticipate both tunable optical response in interacting graphene disks and refractive index sensing via the response of graphene squares to ambient media. These models open up a new way of controlling the structure's performance and refining it to meet our application-specific requirements.

Keywords: terahertz wave, graphene metasurface, circuit modeling, periodic arrays