Hyperbolic metasurfaces

The properties of surface plasmons supported by infinitesimally thin hyperbolic metasurfaces are investigated in detail. Hyperbolic metasurfaces are rigorously modelled using uniaxial conductivity tensors, thus taking into account their combined dielectric/metallic nature. The dispersion relation of the supported modes is analytically derived and asymptotically simplified to closely follow the branches of the TM hyperbolic isofrequency contour. The features of the supported plasmons include i) an ideally infinite field confinement, limited in practice by the presence of losses and the periodicity of the engineered structure, and ii) propagation along specific directions within the sheet, which can be controlled by manipulating the components of the metasurface conductivity tensor. We envision that hyperbolic metasurfaces may find application in guided plasmonic devices, enhancing the spontaneous emission rate of emitters, imaging and sensing.