Vortex clusters bifurcating from multipoles and second-order ring solitons

We address the existence, stability, and propagation dynamics of multipole solitons and vortex clusters in cubicquintic media subject to a harmonic trapping potential.We found that vortex clusters comprising N off centered vortices with alternating topological charges m equal to +(-)1, evenly distributed on a ring, can bifurcate from a multipole soliton for N less than or equal to 4 and from a second-order ring soliton for N greater than 4. Rigorous linear stability analysis, corroborated by direct numerical simulations, shows that upper branch vortex clusters with N equal to 2 and 4 remain stable over a wide range of the propagation constant. Thus, we reveal the formation mechanism of vortex clusters.