Graphene-based multi-layers THz absorber: Circuit model representation

Leveraging both concept and method, a unique THz wave absorber is presented. Three layers include dielectric and graphene patterns that are exploited on top of a thick golden surface to ensure zero THz waves transmitting via the structure. Auspicious dual bias scheme is used for periodic arrays of graphene ribbons in the first layer while the second layer consists of periodic arrays of graphene disk. Also, the top layer is a continuous graphene sheet to enhance the whole absorption. All involved components are modeled via the developed circuit model approach as passive circuit elements. This leads to an exclusive impedance calculation of the structure, paves the way to the fully predictable behavior of the device. Thanks to impedance matching theory, the structure parameters are tuned to obtain perfect dual-band absorption at 5.5THz and 8.5THz frequencies. Ample simulations verify the robustness of the structure versus geometrical parameters while a great capability of tuning absorption peaks is achieved via chemical potentials variation. Such a robust and tunable absorber is attractive for designing optical sensors, detectors, and modulators.