Mimicking surface polaritons for unpolarized light with high-permittivity materials

Tailoring near-field optical phenomena often requires excitation of surface plasmon polaritons (SPPs) or surface phonon polaritons (SPhPs), surface waves at the interface between media with electric permittivities of opposite sign. Despite their unprecedented field confinement, surface polaritons are limited by polarization: only transverse magnetic fields enable their excitation, leaving transverse electric fields unexploited. By contrast, guided modes in positive permittivity materials occur for both linear polarizations, however, they typically cannot compete with SPPs and SPhPs in terms of confinement. Here we show that omnipolarization guided modes in materials with high-permittivity resonances can reach confinement factors similar to SPPs and SPhPs, while surpassing them in terms of propagation distance. We explore the cases of silicon carbide and transition-metal dichalcogenides near their permittivity resonances, and compare with SPhPs in silicon carbide and SPPs in silver, at infrared and visible frequencies, respectively