Compact Polarization Beam Splitter in Silicon Photonics

Based on the asymmetric directional coupler, a polarization beam splitter based on silicon on Insulator (SOI) platform is designed for the wavelength range of 1500nm-1600nm in optical communication in this letter. The asymmetric directional coupler is composed of a regular strip shape waveguide and a sub-wavelength grating waveguide. The influence of the grating period, grating depth, and duty cycle on its polarization characteristics is analyzed. The simulation results show that the polarization extinction ratio (PER) of TE polarization is 20-23 dB and the insertion loss(IL) is 0.01-0.04dB, in the wavelength range of 1500-1600nm, while the PER of TM polarization is 15-26 dB and the IL is 0.3-0.6dB. Especially, the PER and IL are 21 dB (26 dB) and 0.31 dB (0.26 dB) for TE (TM) at the wavelength of 1550 nm. Moreover, the minimum feature size of this device is 25 mu m2. It can be effectively used in semiconductor photoelectronic devices.