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 cross-phase-modulation 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 built not only of fundamental solitons, but of multipoles, too.
Kartashov, Y. [et al.]. Self-trapping and splitting of bright vector solitons under inhomogeneous defocusing nonlinearities. "Optics letters", 01 Desembre 2011, vol. 36, núm. 23, p. 4587-4589.