Effect of quintic nonlinearity on soliton collisions in optical fibers

We investigate the effect of quintic nonlinearity on collisions between solitons in different frequency channels in optical fibers. We calculate the intensity and dynamics of the collision-induced emitted radiation and changes in the soliton parameters due to the collision. This is done by means of a perturbation theory with two small parameters: the quintic nonlinearity coefficient ϵq, and the reciprocal of the inter-channel frequency difference 1/β. We find that the amplitude of the collision-induced emitted radiation is proportional to ϵq/β. This radiation can be described as originating from a variation in the Kerr nonlinearity coefficient with respect to distance along the fiber. We also find that the only other effect of quintic nonlinearity on the collision up to second order in the perturbation theory is an additional phase shift proportional to ϵq/β. The results obtained by our numerical simulations of the perturbed nonlinear Schrödinger equation are in very good agreement with theory.