Metasurface pathways for surface guiding of confined terahertz spoof surface plasmon polaritons on routes with subwavelength width

We report the realization of ultrathin metallic metasurface pathways that can guide strongly confined spoof surface plasmon polaritons (SSPP's) at terahertz frequencies. The subwavelength metasurface path width enables a tight in-plane confinement of the SSPPs, which allows to route them along arbitrary signal paths without the loss of their field confinement perpendicular to the surface. By the use of a near-field imaging terahertz spectroscope, we were able to investigate propagating SSPP's on fabricated samples, which delivers new insights into the spatio-temporal and spectral properties of these guiding structures.