Low-loss plasmonic hybrid optical ridge waveguide on silicon-on-insulator substrate

To achieve low loss and complete confinement of light, we propose and study a plasmonic hybrid optical waveguide fabricated on an silicon-on-insulator substrate. Using controlled oxidation and etching processes, a deep submicrometer Si core is fabricated based on UV photolithography patterning. The as-fabricated waveguide demonstrates a very low propagation loss of 1.6 dB/mm at 1550 nm. The numerical study discloses the hybrid characteristics of the mode. It is shown that the optical power of the waveguiding mode distributes more in the high-index Si-core region, and the metal cover further confines the light beyond the diffraction limit. The hybrid waveguide may be applied in compact, high-density Si photonic integrated circuits.