THz and microwave surface plasmon polaritons on ultrathin corrugated metallic strips

Abstract

In the terahertz and microwave frequencies, natural surface plasmon polaritons (SPPs) do not exist, but can be supported by plasmonic metamaterials, which are usually periodic structures decorated on metallic surfaces. In this review paper, we introduce a kind of planar or flexible plasmonic metamaterial on thin metal films with nearly zero thickness. From theoretical simulations and experiments, we demonstrate that spoof SPPs can propagate along an ultrathin corrugated metallic strip and be highly sustained along two orthogonal directions of the strip in the terahertz and microwave regions with excellent performance, such as broadband, good modal shape, long propagation distance, and low bending loss. We also show that such ultrathin corrugated metallic strip can be printed on flexible dielectric film to support conformal surface plasmons (CSPs) on arbitrary surfaces. The ability to bend spoof SPPs freely makes the ultrathin plasmonic metamaterial more practical to produce plasmonic devices. We have designed and simulated broadband planar and flexible SPP waveguide, 90o bend, beam splitter, and ring resonator in the terahertz frequency, which exhibit excellent performance. Experiments in the microwave frequency validate the feasibility of the ultrathin plasmonic metamaterial.