Impacts of self-frequency shift to soliton interactions and its suppression

Under the influence of self-frequency shift, the interactions between in-phase and out-phase neighboring fundamental and second-order optical solitons are investigated numerically, and the impacts of soliton interactions to timing jitter are analyzed. It is found that under the influence of self-frequency shift, the periodic collision of neighboring fundamental in-phase soliton pair is broken. They are apart from each other rapidly after one collision and the self-frequency shift phenomenon is much more obvious after the collision. While for neighboring out-phase fundamental soliton pair, two solitons both shift to the dropping edge and the impacts of self-frequency shift are weaker than that of in-phase soliton pair. For second-order solitons, either in-phase or out-phase soliton pair will be split. Two split stronger solitons will collide with each other during the propagation in the optical fiber and the difference between in-phase soliton pair and out-phase soliton pair exists that the interactions of out-phase pair is weaker than that of in-phase soliton pair and the collision distance of out-phase pair is much longer than that of in-phase soliton pair. A nonlinear gain can be used to effectively suppress soliton interactions as well as effects of soliton self-frequency shift, and stabilize the soliton propagation.