LAUSR

In this paper, we propose a novel absorber that combines a multi-layer film structure with graphene. The proposed structure is delicately simulated using a commercial finite element method. We combine an equivalent circuit model with parameter inversion to achieve a new method of analyzing the physical mechanism of selective absorption. The results show that four gradually decreasing peaks of ultra-high absorption are formed within 0–1.1 THz, and the maximum absorptance is near 100%. Numerical simulation and theoretical calculation are in good agreement. Due to the symmetry of the structure and the locality of surface plasmon resonance, the proposed structure is insensitive to the incident angle and the polarization state of incident light. By changing the Fermi level of the graphene, the coordination of the device is realized. By changing the height of the dielectric material to change the resonance frequency, the working frequency band is increased from 0–1.1 THz to 0–1.9 THz, and the four absorption peaks become three, which are used as sensor applications. The sensitivity of the sensors is 50 GHz RIU−1, the coefficient of the determination value (R 2) obtained by linear fitting is 0.9989, and the value of the limit of detection is 5.9 × 10−5 RIU. The results show that our proposed devices have great potential in the practical application of terahertz technology absorbers and refractive index sensors.