Diffraction-free propagation of terahertz spoof surface plasmon polaritons on metasurfaces with hyperbolic dispersion

We report the implementation of metasurfaces with hyperbolic dispersion that route propagating terahertz spoof surface-plasmon polaritons on highly confined, almost diffraction-free signal paths. We also tuned their propagation angle by adjusting the hyperbolic isofrequency contour.