Hyper-Plasmonics: hyperbolic modes of a metal-dielectric interface

Plasmon resonance, with strong coupling of light to electrons at a metal-dielectric interface, allows light confinement and control at subwavelength scale. It's fundamentally limited by the inherent mobility of the electrons, leading to the corresponding non-locality of the electromagnetic response. We report that this non-locality also results in the formation of a hyperbolic layer near the metal-dielectric interface, with a strong anisotropy of its electromagnetic response. While the resulting "hyperbolic blockade" leads to the suppression of the conventional plasmon resonance, the hyperbolic layer also supports an entirely new class of surface waves, that offer longer propagation distance and stronger field confinement, simultaneously. Furthermore, these "hyper-plasmons" are not limited to the proximity of the plasmon resonance, which dramatically extends the operational bandwidth of plasmonic devices.