Polarization selective resonator

An optical device comprising a resonator waveguide and a filter waveguide optically coupled with the resonator waveguide at a coupling region is disclosed. The resonator waveguide is configured to support at least a first polarization mode and a second polarization mode, the second polarization mode being an operational mode of the resonator waveguide. The resonator waveguide has a first effective index associated with the first polarization mode and a second effective index associated with the second polarization mode. The first polarization mode is in a different polarization than the second polarization mode. The filter waveguide has, in the coupling region, a filter first effective index associated with the first polarization mode, wherein the filter first effective index at least approximately matches with the first effective index of the resonator waveguide such that the first polarization mode is filtered out of the resonator waveguide.