Diffraction-induced polarization effects in optical pattern formation

We show theoretically that patterns with concentric rings of bright or dark spots made up by modes with coprime azimuthal indexes may arise in codimension one bifurcations in optical systems with a metallic diffractor, a polarizer, and a nonlinear medium. These patterns are a consequence of diffraction-induced polarization in systems without polarization dynamics. As an example of this type of system, we investigate numerically the symmetry-breaking bifurcations of a ring laser with a metallic duct and a polarizer inside the optical cavity.