Multiple-charged optical vortex solitons: Existence and stability in saturable Kerr-type nonlinear media

Multiple-charged optical vortex solitons (OVSs) are generated in a thermal nonlinear medium with saturation. The respective soliton constants are found to be linearly proportional to the topological charges. The linear stability analysis and the numerical simulations indicate a rich variety of instability scenaria depending on the type of perturbation. The saturation of the nonlinearity is shown to be able to slow down the decay of multiple charged dark beams at an intermediate evolution stage and to prevent their ultimate decay into charge-one OVSs. This concept is experimentally verified by the experimental observation of a partial decay of a triple-charged optical vortex beam.