Tunable THz perfect absorber with two absorption peaks based on graphene microribbons

Perfect absorption is characterised by the complete suppression of incident and reflected electromagnetic wave, and complete dissipation of the incident energy. A tunable perfect terahertz (THz) absorber with two absorption peaks based on graphene is presented. The proposed structure consists of graphene microribbons sandwiched between aluminium oxide strips and polymethyl methacrylate slab on a silicon dioxide (SiO2) layer which is covered by periodic gold (Au) ribbons, and the SiO2 layer is supported by the Au substrate.

The influence of the structural parameters on the absorption performance was analysed too. Especially, graphene can be used to design tunable THz devices due to its tunability of sheet conductivity which could be controlled by applying a bias voltage or chemical doping. A single-band perfect absorption can be achieved when the chemical potential is set to 0.1 eV.

Interestingly, when the chemical potential changed to 0.6 eV, a dual-band absorption spectrum is obtained with absorption efficiency of the two peaks more than 90%. These results imply that the characteristics of graphene-based surface plasmon could be used to design novel THz devices in future.