Tunable terahertz perfect absorber with a graphene-based double split-ring structure

In this paper, we describe a tunable perfect absorber based on a graphene metamaterial. It consists of a square split graphene ring and a round split graphene ring. Using silicon as the base, gold, silicon dioxide, and graphene are placed layer by layer in sequence. The results of simulations performed using CST Microwave Studio indicate that the double split-ring structure possesses two absorption peaks at 10.96 THz and 12.71 THz, with absorption efficiencies of 99.7% and 99.4%, respectively, which approach perfect absorption. The permittivity of graphene can be controlled by the plus gate voltage, which results in dynamic control over the absorption peaks. Furthermore, owing to the small impact on the resonance frequency, the relaxation time may be applied to manipulate the absorption peaks. In addition, we also discuss how different structural parameters affect absorption. Lastly, we conclude that the proposed graphene-based absorber has a wide-angle incoming characteristic and great potential in infrared, filter, and terahertz detection. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement