Theoretical design of a triple-band perfect metamaterial absorber based on graphene with wide-angle insensitivity

Abstract

This paper proposes a square ring-shaped triple-band perfect absorber based on graphene with silicon as the substrate, gold as the reflector and a thin dielectric layer of silicon dioxide. After simulation by the FDTD method, the numerical results show that the absorption spectrum based on the periodic array structure of graphene exhibits three perfect absorption peaks in the terahertz band, corresponding to 25.53 μm, 36.44 μm and 53.44 μm, respectively, and they all reach 99% absorption rate. By changing the gate voltage, the material parameters of graphene can be easily adjusted, so as to achieve dynamic control of the absorption characteristics of the absorber. Due to the high symmetry of the structure, it has a good angular polarization tolerance in the far infrared band. In addition, the obvious spectral shift caused by the change of surrounding environment refractive index and the values of sensitivity (S) and figure of merit (FOM) are all indicates that our absorber has certain application prospects in the field of sensing. Furthermore, our absorber has shown great application potential in light detection in infrared and terahertz band as a consequence of the strong tunability.