We show that ringlike localized gain landscapes imprinted in focusing cubic (Kerr) nonlinear media with strong two-photon absorption support new types of stable higher-order vortex solitons containing multiple phase singularities nested inside a single core. The phase singularities are found to rotate around the center of the gain landscape, with the rotation period being determined by the strength of the gain and the nonlinear absorption.
Borovkova, O. [et al.]. Rotating vortex solitons supported by localized gain. "Optics letters", 15 Maig 2011, vol. 36, núm. 10, p. 1936-1938.