Design of thick polarization beam splitter based on a bridged directional coupler with 400 nm high silicon cores

Abstract

We introduce a thick integrated polarization beam splitter (PBS) based on a bridged directional coupler (DC) with three planar waveguides of 400-nm-high silicon core layer. Contrary to the conventional thin DC-type PBSs using the cross coupling effect of the TM modes, the thick PBS utilizes the cross coupling effect of TE modes because the effective refractive index of the fundamental TM mode is larger than that of the fundamental TE mode in the single mode condition. At the 1,550 nm wavelength, the peak polarization-extinction-ratios (PERs) of the PBS device are calculated to be 33.81 dB and 41.09 dB for TM and TE modes, respectively, and its corresponding insertion losses (ILs) are 1.58 dB and 0.08 dB when its main input and output waveguide width, a bridge waveguide width, waveguide gap and coupling length are 190 nm, 270 nm, 560 nm, and 32.6 μm, respectively.