Numerical Simulation and Equivalent Circuit Model of Multi-Band Terahertz Absorber Composed of Double-Sided Graphene Comb Resonator Array

Multi-band terahertz (THz) absorber based on a non-symmetric double-sided graphene comb resonator array is designed and simulated by the finite element method (FEM) in CST Software. Then, an equivalent circuit model (ECM) based on admittance with a fast MATLAB code is proposed to analyze the absorber in the THz region. The admittance-based ECM approach could be used for any metamaterial absorber containing one layer of resonators sandwiched between two dielectric slabs and backed by a metal layer consisting of a layer of resonators with a thickness much smaller than the minimum wavelength in the considered wavelength range. The proposed absorber is dynamically tunable with a one-layered resonator array. It has strong linear dichroism (LD) response of 98% and the frequency range of 0.7-5 THz with absorption > 96%: two absorption bands for TE mode and three for TM mode. The proposed absorber can be used in polarization-sensitive devices and systems in the THz region. The ECM model of the metastructure was derived to provide an efficient approach to analyzing the performance of the absorber. The FEM simulation results are in good agreement with the ECM ones.