Terahertz Range Elementary Dipole Excitation of a Thin Dielectric Disk Sandwiched between Two Graphene Covers: Integral Equation Analysis

We study, using the integral equation technique, the scattering of the field radiated by an elementary dipole, by a thin dielectric disk sandwiched between two conformal graphene covers, on the top and bottom faces. To build a mathematical model of such scatterer, we use the generalized boundary condition in the form first obtained by Mitzner and Bleszynski et al. and generalized by Karlsson. This enables us to derive dual integral equations in the disk plane for the Hankel transforms of the tangential electric and magnetic field components, and cast it to a set of two coupled Fredholm second-kind integral equations. The latter equations are discretized and solved numerically with the guaranteed convergence. We compute and plot the power radiated by an elementary magnetic dipole placed above such a composite disk, in the THz range. This reveals that the studied scatterer is a complicated open resonator supporting the low-frequency plasmon modes and the high-frequency dielectric-disk modes.