Coordination multi-band absorbers with patterned irrelevant graphene patches based on multi-layer film structures

In this paper, we propose novel absorbers with periodic stacking of graphene metasurface based on multilayer film structures. The proposed structure is delicately simulated by using the commercial finite element method (FEM). We combine equivalent circuit model (ECM) with parameter inversion to achieve new method to analyse the physical mechanism of selective absorption. The results show that four gradually decreasing peaks of ultra-high absorption are formed within 0-1.1THz, 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 SPR, the proposed structures are insensitive to the incident angle and polarization state of incident light. By changing the Fermi level of 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 0-1.1THz to 0-1.9THz, and the four absorption peaks become three, which are used as sensor applications. The sensitivity of the sensors is 50GHz/RIU, the coefficient of determination value (R2) obtained by linear fitting is 0.9989, and the value of the limit of detection (LOD) is 5.9 ×10-5RIU. The results show that our proposed devices have great potential in the practical application of terahertz technology absorbers and refractive index sensors.