A polarization independent surface wave coupler based on a phase gradient metasurface

A phase gradient metasurface (PGM) is an anisotropic metallic array structure with subwavelength thickness, which can produce an in-plane phase gradient in the incident wave. It can be used to control the shape of the wave front, the propagation direction, and the polarization of the reflected/refracted waves with more freedom. In this paper, the combined-splitresonant- rings (CSRR) is proposed as the sub-unit resonators so as to achieve the PGM. At the central frequency f = 3.3 GHz, the PGM is designed to work as a surface electromagnetic wave (SEMW) coupler. The necessary momentum for surface wave coupling is compensated by the phase gradient provided by the PGM. The coupling efficiency extracted from the simulated reflection coefficient and the distributions of the electromagnetic fields indicate that this PGM is a highly-efficient and polarization independent SEMW coupler under normal incidence. Because of the characteristics of high coupling efficiency, polarization-independence, and ultra-thin structure, significant applications in invisibility can be envisaged.