Transverse phase shielding solitons in the degenerated optical parametric oscillator

Localized structures in optics have attracted attention for their potential applications in telecommunications and information storage. In the present work, localized structures with non-uniform phase structure in the degenerate optical parametrical oscillator are reported and elucidated. Dissipative solitons with non-uniform phase structures in parametrically driven systems have been already observed in prototype models being found in two typical shapes: symmetrical and asymmetrical. In contrast, the phase structure in degenerate optical parametrical oscillator is always symmetrical, showing a pronounced bell-shaped phase. We show that the nonlinear saturation present in this physical system is responsible of a relaxation dynamics and this symmetry. Probing that real physical systems exhibit always this unique type of localized structure with phase structure. An adequate analytical description for the phase, based on a simple model, is achieved showing that such structure is controlled by the interplay between the detuning, the external pump and the losses of the cavity. Numerical simulations present quite agreement with theoretical predictions.