Ultra-broadband silicon polarization splitter-rotator based on the multi-mode waveguide

mode goes through the PSR with negligible conversion and coupling. Only one-step etching is required for the proposed PSR. The fabricated PSR shows a high extinction ratio > 30.82 dB and a low loss < 0.57 dB at the central wavelength. The extinction ratio is > 20 dB over an ultra-broad wavelength band > 85 nm.