High-extinction ratio polarization splitter based on an asymmetric directional coupler and on-chip polarizers on a silicon photonics platform

A high performance compact silicon photonics polarization splitter is proposed and demonstrated. The splitter is based on an asymmetric directional coupler. High extinction ratios at the through and drop ports of the polarization splitter are achieved by using an on-chip TE-pass polarizer and a TM-pass polarizer, respectively. The splitter, implemented on a silicon-on-insulator platform with a 220 nm-thick silicon device layer, has a measured insertion loss lower than 1 dB (for both TE and TM modes) and extinction ratio greater than 25 dB (for TM mode) and greater than 36 dB (for TE mode), in the wavelength range from 1.5 µm to 1.6 µm. The footprint of the device is 12 µm × 15 µm.