Stable higher-charge discrete vortices in hexagonal optical lattices
  We show that double-charge discrete optical vortices may be completely stable in hexagonal photonic lattices where single-charge vortices always exhibit dynamical instabilities. Even when unstable the double-charge vortices typically have a much weaker instability than the single-charge vortices, and thus their breakup occurs at longer propagation distances. 
Kody J.H. Law, P. G. Kevrekidis, Tristram J. Alexander, Wieslaw   Krolikowski, and Yuri S. Kivshar