Shallow-etched silicon grating waveguide based polarizing beam splitter

A compact asymmetrical directional coupler composed of 70-nm-deep shallow etched dual grating structure waveguide and a 7.4-μm long coupling length, is proposed and fabricated to realize a broadband and high-extinction-ratio polarizing beam splitter. By carefully optimizing the structural parameters, the cross-coupling for TM light can be realized while little coupling happens for TE wave, which would have a broad application prospect for silicon-based photonics.