Reflection and transmission properties of a graphene-dielectric-thin resistive layer structure in the THz range

Abstract

We studied two-dimensional planar dielectric slab, sandwiched by graphene and thin resistive layer from two sides. Problem geometry is illuminated by a H-polarized electromagnetic plane wave from upper side. It is expected to observe the reflection and transmission performance of such a composite slab geometry depending on the electrical and geometrical parameters. We used the local reflection and transmission coefficients method to determine the overall performance. It is seen that the proper selection of the electrical resistivity of the thin resistive layer reduces the reflection from lower boundary of slab and the electrical thickness becomes less important for high THz range. Then, the geometry turns to be an air-dielectric interface. This is a novel finding and completely different from the pure dielectric slab without coatings which has frequency dependent characteristics. Also higher reflections are observed due to the higher conductivity of graphene in the low THz range. Furthermore, a sample finite plate is constructed in a same manner and it is modeled by using CST software. Presented method using equivalent 2D profile model and CST results are compared and very good consistency is observed. In both cases, the reflection can be controlled with the chemical potential at low THz range and the selection of the relative permittivity of the dielectric material determines the reflectance level at higher THz scale. We demonstrate these statements in the numerical results section for various problem parameters and angle of incidence.