Graphene-based tunable quad-band fan-shaped split-ring metamaterial absorber and refractive index sensor for THz spectrum

摘要

A novel quad-band, fan-shaped split-ring metamaterial absorber and refractive index sensor for THz spectrum is presented in this paper. The structure is based on periodic graphene cells and layers of SiO_2 and gold. The layers of graphene, SiO_2, and gold are stacked on top of each other and the analyte is located on the top of the structure. It is shown that by changing graphene's chemical potential the resonance frequencies can be tuned and the sensor performance and the absorption efficiency can be enhanced. The senor is numerically simulated using finite element method which shows four absorption peaks for the frequency range of 3 THz to 11 THz. Examination of the simulation results for different analyte refractive indices reveals that the obtained absorption peaks have sensitivities equal to 0.913, 1.55, 1.96, and 2.137 nm/RIU, where RIU stands for the refractive index. The results obtained in this paper make the designed sensor as a good choice for biomedical applications.