Polarization rotation in periodic loaded rib waveguides

Polarization rotation in an asymmetric periodic loaded rib waveguide is analyzed by a scalar coupled-mode theory with vector correction. The scalar modes of the dielectric loaded rib waveguide are calculated by using a simple variational method. The polarization rotation is found to be caused by a geometric effect due to the asymmetric loading of the waveguide. By phase-matching the two polarized modes through the periodic loading, complete polarization rotation can be achieved