Ultrabroadband Silicon-on-Insulator Polarization Beam Splitter Based on Cascaded Mode-Sorting Asymmetric Y-Junctions

A very novel silicon-on-insulator polarization beam splitter is proposed based on cascaded mode-sorting asymmetric Y-junctions. The width and length of each Y-junction are optimized to achieve correct mode sorting with high conversion efficiency. The numerical simulation results show that the mode conversion efficiency increases with the length of the Y-junction for the waveguide widths varying in a large range. This proposed device has <; 0.7 dB insertion loss with > 22 dB polarization extinction ratio in an ultrabroad wavelength range from 1450 to 1750 nm. Fabrication tolerance analysis is also performed with respect to the deviation in device width and height. With such a broad operating bandwidth and robust fabrication tolerance, this device offers potential applications for complementary metal oxide semiconductor (CMOS)-compatible polarization diversity operating across the S, C, L, and U optical communication bands, particularly in the booming 100-Gb/s coherent optical communications based on silicon photonics technology.