On-chip polarization beam splitter with multimode operation in a SOI waveguide

The polarization beam splitter (PBS) based on the directional coupler is numerically investigated to operate transverse-electric (TE) and transverse-magnetic (TM) modes including high-order modes. Based on the phase-matching condition, all TM-polarization modes are switched from the bus waveguide to the adjacent waveguide without changing the spatial profile of the electric field and mode order while all TE-polarization modes go along the bus waveguide without significant coupling. The results show a low cross talk characteristic (>20 dB at 1.55 mu m) and big fabrication tolerance (delta w = +/- 20 nm). It becomes an essential supplement for polarization splitting with multimode operation in photonics integrated circuits. (C) 2018 The Japan Society of Applied Physics