Hybrid Plasmonic Waveguide Comprising a Semiconductor Nanowire and Metal Ridge for Low-Loss Propagation and Nanoscale Confinement

The proposed hybrid plasmonic waveguide comprises a semiconductor cylindrical nanowire embedded in a low-index dielectric above a metallic substrate with two grooves carved into the surface, between which a nanoscale metallic ridge is formed. Comparing the original hybrid plasmonic structure having a flat metal surface with the proposed structure significantly reduces the lateral mode size of the hybrid modes, and moderately increases the propagation distance. The mode area and propagation distance dependences on the geometry and material parameters are studied. A parametric plot of the figure of merit shows that the proposed structure outperforms the original hybrid structure. The mode performances can be improved further by rounding the metallic ridge corners with the maximum radius. Under an equal confinement of light, the propagation distance of the present structure is three times larger than that of the previously published hybrid structure.