Vortex solitons in media with competing cubic–quintic nonlinearity and rotational PT-symmetric potentials

This study presents the generation and dynamics of vortex solitons (VSs) in media featuring cubic–quintic nonlinearity and rotational parity-time (PT) symmetric potentials. The findings demonstrate that such potentials stabilize VSs carrying topological charges m up to 3. The formation and stability domains of these VSs exhibit a strong dependence on the imaginary lattice component, strength of the competing nonlinearities, and rotation frequency. Significantly, the longitudinal twist provides essential strategy for stabilizing VSs with finite m, while structures possessing higher |m| exhibit substantially reduced stability regions. The stability of VSs depends on the sign of the topological charge and rotation frequency. For stable VSs, the cubic nonlinearity has to be positive (self-focusing), whereas the quintic term may exhibit either positive or negative values. Remarkably, stable VS parameter spaces can persist even near the PT-symmetry breaking threshold, where the linear lattice spectrum becomes complex.