Tailor the surface-wave properties of a plasmonic metal by a metamaterial capping

Surface waves (SWs) are eigen electromagnetic (EM) surface modes bounded on dielectric/metal interfaces, which exhibit many fascinating properties (e.g., subwavelength resolution and dramatic local-field enhancement) and thus have numerous applications in practice. However, Surface waves supported by a conventional plasmonic metal suffer many restrictions (say, they can have transverse-magnetic (TM) polarizations). Here, we show that putting an ultra-thin anisotropic metamaterial layer on a plasmonic surface significantly enriches the Surface wave  characteristics of the system, which now supports Surface waves with both TM and transverse-electric (TE) polarizations simultaneously. In addition, the generated Surface waves exhibit hybridized polarization characteristics in certain cases, and a Surface waves band gap opens within a particular propagation direction range. We designed and fabricated a realistic structure based on the proposed model, and combined microwave experiments with full-wave simulations to verify the fascinating theoretical predictions. Our findings can have potential applications in practice (e.g., building planar subwavelength EM devices/circuits for signal transport, etc. ).