Ultra-wideband terahertz graphene absorber using circuit model

In this work, a novel solution for designing an ultra-wideband terahertz graphene-based absorber by exploiting the periodic arrays of graphene ribbons (PAGRs) and graphene continuous sheet (GCS) is presented. Here we develop and extend a transmission line method to describe the absorber structure as circuit elements. Regarding impedance-matching concept and using analytical circuit model of PAGRs and GCS which recently have been proposed, different PAGRs have been used to gain ultra-wide bandwidth. As a result, a bandwidth of 90% absorption is extended up to 130% and 146% of the central frequency with three and four layers of graphene, respectively. Excellent performance of the proposed method regarding computation time (showing more than five orders of magnitude reduction in runtime) and memory sources besides producing results with an acceptable agreement with the results of full-wave simulations (with an error less than 5%), nominates it as a promising approach to design and simulate other sub-wavelength graphene-based devices and; moreover, since the proposed structure is a multi-layer one, it can be manufactured by chemical vapor deposition.