Highly confined guiding of low-loss plasmon waves in hybrid metal-dielectric slot waveguides.

We report the observation of strongly confined plasmon modes in hybridized metal-dielectric slot waveguides, which consist of semiconductor-insulator-semiconductor nanostructures embedded inside the low-index gaps of conventional hybrid plasmonic configurations. Owing to the combined effects induced by the high-refractive-index-contrast dielectric slot and semiconductor-insulator-metal configurations, tight field localization (Aeff ~ λ(2)/1250-λ(2)/55) in conjunction with large propagation distances (L ~ 70-180 μm) can be realized simultaneously at telecommunication wavelength. Through comprehensive numerical simulations, the characteristics of the fundamental hybrid modes are revealed in detail by optimizing key structural parameters of the waveguides. The advantages over their traditional hybrid waveguiding counterparts are unraveled. In addition, the possibilities of extending our current design into other metal/dielectric composites are also discussed. Our studies regarding hybrid metal-dielectric slot structures and their alternatives in this paper are expected to provide effective approaches for the enhancement of traditional hybrid modes' properties and open up new opportunities for the constructions of high-performance plasmon waveguides and devices.