Polarization-insensitive unidirectional spoof surface plasmon polaritons coupling by gradient metasurface**Project supported by the China Postdoctoral Science Foundation (Grant No. 2015M580849) and the National Natural Science Foundation of China (Grant Nos. 61471292, 61501365, 61471388, 61331005, 41404095, and 41390454).

Abstract

A polarization-insensitive unidirectional spoof surface plasmon polariton (SPP) coupler mediated by a gradient metasurface is proposed. The field distributions and average Poynting vector of the coupled spoof SPPs are analyzed. The simulated and experimental results support the theoretical analysis and indicate that the designed gradient metasurface can couple both the parallel-polarized and normally-polarized incident waves to the spoof SPPs propagating in the same direction at about 5 GHz.