An efficient orthogonal coupler for silicon photonics with the degenerate plasmonic modes

An orthogonal coupling structure is proposed to collect the near-infrared lightwaves into a SiO₂/Si/SiO₂slab waveguide, which is mainly based on the generation of degenerate plasmonic longitudinal modes in an Ag/SiO₂/Ag V groove. The coupling efficiency of the proposed plasmonic coupler is higher than 50% in the wavelength range from 1300 nm to 1748 nm. Besides, the highest coupling efficiency (lowest coupling loss) is 87.2% (0.60 dB) at the wavelength of 1531 nm. The proposed plasmonic structure on top of the silicon-on-insulator substrate can facilitate the development of co-packaged optics.