Domain coexistence in two-dimensional optical patterns.

We give evidence of coexisting transverse patterns of different symmetry in an optical beam circulating in a loop which contains a nonlinear medium. The symmetry of the patterns is controlled by the azimuthal rotation introduced in the feedback loop (nonlocality), while the competition is ruled by the input intensity which determines the distance from threshold (nonlinearity). Domains corresponding to patterns with different wave vectors (either different wavelength or different orientation) coexist, nucleating and moving. This gives rise to a complex spatiotemporal dynamics which is characterized by means of suitable collective indicators.