Hybrid nanowedge plasmonic waveguide for low loss propagation with ultra-deep-subwavelength mode confinement

In this Letter, a novel waveguide based on hybrid surface plasmon polaritons (HSPPs) is proposed and numerically analyzed. This waveguide consists of two dielectric nanowires placed on both sides of a nanowedge-patterned metal film, which can confine light in the ultra-deep-subwavelength region (ranging from λ²/4000 to λ²/400) with a long propagation length (ranging from 1200 to 3500 μm). Compared to a previous HSPPs waveguide without the nanowedges, with the same propagation length, our proposed structure has much higher mode confinement with 1 order of magnitude smaller normalized mode area. An investigation of the effect of structural perturbations indicates that our proposed waveguide also has good tolerance of fabrication errors. The proposed waveguide could be an interesting alternative structure to realize nanolasers and optical trapping.