Theoretical Design of Graphene-Based Bi-Functional Tunable Terahertz Metasurfaces

Abstract

Tunable multifunctional metasurface has wide application such as optical electromagnetics and material science. In this paper, a terahertz (THz) metasurface based on double graphene split-ring resonators (GSRRs) are theoretically demonstrated, integrating dual-band absorption and plasmon-induced transparency (PIT) filtering effect. The structure is composed of a monolayer of graphene arrays with periodic patterns and a metal ground surface partitioned by a silicon dioxide dielectric layer. When the initial structure of unit cell is three-layer sandwich structure (bottom metal plate), its dual-frequency absorption spectra appears two peaks at 2.50 THZ and 3.38 THz, which are 99.98% and 97.94%, respectively. Then the mechanism of double band absorption is explained by analyzing the distribution of surface current and electric intensity of the absorbent material. When the initial arrangement of the cell is a double layer structure (without the bottom metal plate), the PIT effect will occur when the incident wave is y-polarized. And in a certain range to achieve more than 90% of the transmission. In addition, CST simulations demonstrate that the designed model supports changing the operating frequency by adjusting the Fermi energy of graphene The dual-function terahertz metasurface proposed in this work has broad application prospects in broadband communication, terahertz imaging and industrial sensors.