High-performance all-silicon polarizer with 415 nm bandwidth

On-chip silicon polarizers have been widely used in polarization controllers. However, there is limited research on all-silicon polarizer covering the whole optical communication band due to the strong waveguide dispersion for silicon waveguides. In this Letter, we demonstrated an all-silicon TE polarizer with high polarization extinction ratio and low insertion loss, working for the whole optical communication band. The device is based on a shallow-etched waveguide realized on a silicon-on-insulator (SOI) platform. The optical field of TE polarization is designed to be tightly confined in the shallow-etched silicon waveguide, while that of TM polarization is weakly confined. As a result, TE polarization propagates through the waveguide with low loss, while TM polarization leaks into the substrate and decays finally. The measurements show that a maximum insertion loss < 0.25 d B and polarization extinction ratio ( P E R ) > 20 d B over an ultrabroad operation band from 1260–1675 nm have been achieved for the proposed polarizer.