INTERPLAY OF LINEAR AND NONLINEAR EFFECTS IN THE FORMATION OF OPTICALVORTICES IN A NONLINEAR RESONATOR

We study the role played by nonlinearities in the formation of optical vortices when the boundary conditions determine the pattern formation in a Fabry-Perot resonator. Particular care is taken to avoid trivial vortices coming from particular Gaussian modes or from the cavity ali gnment. We show that, while the existence of optical vortices is a gen eric linear property of the superpositions of Gaussian modes, their ac tual appearance in the transmitted patterns is controlled by the nonli nearity itself.