Highly confined hybrid plasmonic modes guided by nanowire-embedded-metal grooves for low-loss propagation at 1550 nm

A waveguiding configuration consisting of a semiconductor nanowire embedded in a dielectric-coated V-shaped metal groove is presented. The modal properties of the fundamental quasi-TE hybrid plasmonic mode are investigated at the wavelength of 1550 nm. Simulation results reveal that by tuning the size of the nanowire, the hybridization between the dielectric mode, and plasmonic mode could be effectively controlled. Through appropriate design, the hybrid mode could be strongly localized in the nanowire and the gap regions on each side, featuring both tight-mode confinement and low propagation loss. Besides, the compromise between confinement and loss could also be balanced by controlling the angle or depth of the metal groove. Moreover, it is found that the hybrid mode could exist for a wide geometrical parameter range, even when the corresponding metal groove by itself does not support a guided channel plasmon polariton mode. The proposed hybrid structure is technologically simple and compatible with planar fabrication methods while avoiding alignment errors.