Novel Silica Waveguide-Type Polarization Beam Splitters Based on MMI Coupler With Extraordinary Gratings

Polarization beam splitters (PBSs) are essential components in on-chip coherent optical communication and polarization division multiplexing systems. Due to the isotropic nature of the silica waveguide, both TE and TM polarizations tend to propagate along the same optical path, making polarization separation challenging. A novel silica PBS based on the multimode interference waveguide with extraordinary gratings is theoretical proposed and experimentally demonstrated. Due to the introduced propagation constants difference, the input transverse electric (TE) and transverse magnetic (TM) polarizations can be effectively split. When the polarization extinction ratio is > 10 dB and the transmission loss is < 8 dB for both polarizations, the measured optical bandwidth is 70 nm, which ranges from 1542 nm to 1612 nm. The demonstrated PBS has potentials in low dielectric constant material planar lightwave circuit (PLC) platforms.