Influence of the Raman-effect on solitons in optical fibers

Solitons in optical fibers in presence of Raman effect can form quasi-stationary asymmetric pulses. Radiation of energy away from the solitons always exists but this can be ignored over a range of soliton parameters. We show numerically that arbitrary initial conditions converge to these soliton profiles. Another form of quasi-stationary solutions are bound states of pairs of these solitons. Although they are unstable, the bound states can propagate long distances without changes in their profile. We have also investigated numerically collisions of solitons in presence of Raman effect.