Experimental observation of hybrid TE-TM polarized surface waves supported by a hyperbolic metasurface

Hyperbolic metasurfaces have gained significant attention due to their extraordinary electromagnetic properties to control propagating plane waves, but the excitation and propagation of surface plasmon-polaritons at hyperbolic metasurfaces, called hyperbolic plasmons, have been experimentally observed only recently. However, the advantages of the hyperbolic plasmons, such as hybrid TE-TM polarization discussed below, are not yet fully revealed and analyzed. In this paper, we focus on the numerical and experimental characterization of surface waves in the frequency range from 2 to 8 GHz supported by a hyperbolic metasurface composed of anisotropic metallic Jerusalem crosses printed on a thin dielectric substrate. We show different shapes of equal frequency contours, which correspond to a plethora of excitation and propagation regimes of surface waves. The principal novelty of this work consists in the experimental demonstration of surface waves with hybrid, i.e., mixed TE-TM, polarization. Surface waves with hybrid polarization are a promising tool in a number of applications and phenomena, including polarization converters, plasmonic sensors, plasmon steering over a surface, optical forces, and spin-orbit photonics, and they highlight the impact of on-chip and planar networks.