Three dimensional trajectories of interacting incoherent photorefractive solitons

We investigate theoretically and experimentally the three dimensional propa gation and interaction of mutually incoherent screening spatial solitons in an SBN crystal. We show that the interaction of solitons results in comple x trajectories which typically show partial mutual spiraling, followed by d amped oscillations and the fusion of solitons. This nontrivial behavior is caused by the anisotropy of the nonlinear refractive index change in the cr ystal. [S0031-9007(98)08243-X].