Dual-band ultrasensitive terahertz sensor based on tunable graphene metamaterial absorber

In this paper, we propose a dual-band tunable absorber with a graphene-dielectric-metal structure as a sensor in the terahertz (THz) region. The finite element method (FEM) based on the CST microwave studio software is used in modeling and numerical analysis. Strong interaction between graphene surface plasmon resonance (SPR) and the absorber gives rise to two ultra-narrow perfect absorption peaks, and the position of the resonance frequencies can be adjusted by tuning the chemical potential of graphene in a wide range. In addition, the high symmetry of the absorber brings polarization and angle insensitivity, in which an absorption rate of over 90% can be obtained when the oblique incident angle is close to 80? in the transverse magnetic (TM) mode. For refractive index sensing, the simulation results show that the proposed structure achieves the maximum sensitivity, Q factor, and figure-of-merit (FOM) of 2.475 THz per refractive index unit (THz/RIU), 216.29, and 76.89 RIU-1, respectively. Therefore, we believe that the proposed sensor with such high performance has a promising application for biomedical diagnosis and environmental monitoring.