A Waveguide Polarization Toolset Design Based on Mode Beating

A toolset of waveguide elements is examined, which can be combined to produce polarization functional devices in a single contiguous waveguide. In particular, waveguide implementations of an optical isolator and a polarization modulator are discussed. The waveguide elements, i.e., quasi-phase-matched nonreciprocal polarization mode converter, reciprocal polarization mode converter (R-PMC), and a differential phase shifter, are all based on mode beating. A universal 3-dB R-PMC specification is identified, which suffices for all the polarization functional devices considered here. A full-vectorial modesolver is used to determine the modes in a number of example III-V waveguide structures, and the polarization state evolution is considered by using an averaged Stokes vector illustrated on the Poincaré sphere construct.