High-Efficiency Directional Excitation of Spoof Surface Plasmon Under Arbitrary Illumination

Recent advances in spoof surface plasmon (SSP) have offered enormous opportunities for engineering electromagnetic waves at the subwavelength scale. However, the fundamental limitation of the extremely finite space channels on exciting SSP challenges their practical applications. Here, to the best of our knowledge, a new method that can realize high-efficiency infinite-channel SSP excitation based on hyperbolic plasmonic metasurfaces is proposed. Free-space propagating waves impinging from arbitrary directions can be coupled to SSP owing to the theoretical perfect wave vector match between the modulated incident waves and the hyperbolic plasmonic metasurfaces. A proof-of-method metacoupler working at 8 GHz is designed and fabricated with the novel functionality numerically and experimentally verified by the consistent guide wavelength with theory. Further experimental investigation reveals a total coupling efficiency exceeding 50% for the impinging waves with incidence angles ranging from -44° to 44°. The proposed methodology provides a new route to design multichannel antennas and detectors.