Self-trapping and splitting of bright vector solitons under   inhomogeneous defocusing nonlinearities
  We show that bimodal systems with a spatially nonuniform defocusing cubic nonlinearity, whose strength grows toward the periphery, can support stable two-component solitons. For a sufficiently strong XPM interaction, vector solitons with overlapping components become unstable, while stable families of solitons with spatially separated components emerge. Stable complexes with separated components may be composed not only of fundamental solitons, but of multipoles too. 
Yaroslav V. Kartashov, Victor A. Vysloukh, Lluis Torner, Boris A.   Malomed
physics.optics cond-mat.quant-gas nlin.PS