Dyadic Green's function of plasmonic nano-antenna gratings on natural/artificial anisotropic thin films

We present an efficient technique to use the periodic method of moments (PMOM) in analyzing the plasmonic nano-antenna gratings (PNAGs) on natural/artificial anisotropic thin films. The artificial media are made up of two alternating isotropic regions in which the optic axis is chosen to be parallel to the period of grating due to its more complicated analysis. Dyadic Green's function (DGF) of these structures is obtained by utilizing the equivalent model of transmission line in Fourier domain and considering the plasmonic effects. Such a DGF is used in a series equation formulated for computing the effective electric currents induced on PNAG's surface. Solving such a series equation is carried out using Galerkin's version of PMOM with appropriate sub-domain functions. Using this technique, the scattering characteristics of different examples of double-screen PNAGs with homogeneous natural/inhomogeneous artificial anisotropic thin films are calculated. Assessment of this technique's efficiency is carried out by taking its cost–time and convergence rate vs truncation orders into account. It is shown that by using the developed technique, not only PNAGs with natural/artificial dielectrics can be analyzed within short time but also CPU and memory occupancies are reduced in comparison with commercial Electromagnetic (EM)-solvers.