Proposal for Ultra-Compact Silicon-on-Insulator Waveguide Polarization Converter

We propose an asymmetric silicon-plasmonic hybrid waveguide, which supports two eigen modes with linearly polarized-like electric field distributions and large difference between their propagation constants. Exploiting these mode characteristics of the hybrid waveguide, an ultra-compact and high-performance silicon-on-insulator (SOI) waveguide polarization converter based on multimode interference is designed, which converts quasi-TE polarization mode to quasi-TM polarization mode. Simulation results show that polarization extinction ratio up to 27 dB is reached for an ultra-short conversion length of 610 nm. The bandwidth is 140 nm for an extinction ratio larger than 20 dB. This asymmetric silicon-plasmonic hybrid waveguide may open promising prospects for further minimizing integrated optical circuits on SOI platform.