Study on propagation properties of spoof surface plasmon on metallic square lattice

Abstract

This dissertation presents basic studies on the propagation properties of spoof surface plasmon modes supported on the metallic square lattice in a microwave frequency regime. The propagation characteristics of spoof surface plasmon modes are studied in both real and reciprocal spaces. We propose a method to experimentally determine the constant frequency contours which are obtained from the fast Fourier transforms by using the electric field distribution directly measured over the metallic square lattice. The anisotropy of the measured constant frequency contours supports the presence of the negative refraction and the self-collimation phenomena which are confirmed from the measured electric fields. Bending and splitting properties of the self-collimated beams are also investigated. From the analysis of the constant frequency contours, we find that the concept of total internal reflection at the interfaces between two dielectric mediums can also be applied to the interfaces between the metallic square lattice and air. We show that a line defect created by removing several rods in a row can totally reflect the incoming self-collimated beams. We propose a spoof surface plasmon beam splitter for self-collimated beams at the frequency of 6.06 GHz, where the constant frequency contour is flat. It is shown that the splitting ratio of the self-collimated beam can be controlled by varying the height of rods in the defect. Subwavelength imaging through the spoof surface plasmons on the metallic square lattice lens is demonstrated in simulations, which does not utilize amplification of evanescent waves in a perfect lens. The observed full width at half maximum is about 0.36 at 6.13 GHz. Evanescent and propagating waves generated from the source can be coupled with spoof surface plasmon modes of the metallic square lattice. The convex curvature of the constant frequency contour makes evanescent and propagating waves from the source transfer to the image plane through th...