An ultra-broadband polarizing beam splitter/coupler using asymmetric-waveguides

A high-performance polarizing beam splitter (PBS) is demonstrated by using asymmetrical directional couplers on a 220nm-thick silicon-on-insulator (SOI) photonics platform. The extinction ratio of the PBS with cascaded directional couplers is > 35 dB for both TE and TM polarizations around the central wavelength of 1550 nm. The bandwidths for an extinction ratio of 20 dB and 30 dB are 275 nm and 230 nm, respectively, for TE polarization, as well as > 300 nm and 225 nm, respectively, for TM polarization. The insertion losses for TE polarization are < 0.5 dB with a bandwidth of > 300 nm. The insertion losses for TM polarization are < 1 dB and < 0.5 dB with a bandwidth of 218 nm and 174 nm, respectively.