A compact silicon-on-insulator polarization splitter

A compact directional coupler-based polarization splitter is designed and realized using silicon-on-insulator (SOI) waveguides. Even though silicon does not have any material birefringence, the high index contrast obtained in the SOI platform and reduced waveguide dimensions makes it possible to induce significant birefringence. Polarization splitting is achieved by making use of this geometry-induced birefringence. We demonstrate polarization splitting in devices as short as 120 μm. Even smaller devices can be made using submicron-thick Si waveguides.