Stable Vortex Solitons in Nonlocal Self-Focusing Nonlinear Media
  We reveal that spatially localized vortex solitons become stable in self-focusing nonlinear media when the vortex symmetry-breaking azimuthal instability is eliminated by a nonlocal nonlinear response. We study the main properties of different types of vortex beams and discuss the physical mechanism of the vortex stabilization in spatially nonlocal nonlinear media. 
Alexander Yakimenko, Yuri Zaliznyak, and Yuri Kivshar