Coupled Nonlinear Schrödinger System: Role of Four-Wave Mixing Effect on Nondegenerate Vector Solitons

In this paper, we investigate the role of four-wave mixing effect on thestructure of nondegenerate vector solitons and their collision dynamics. Forthis purpose, we consider the generalized coupled nonlinear Schrödinger(GCNLS) system which describes the evolution and nonlinear interaction of thetwo optical modes. The fundamental as well as higher-order nondegenerate vectorsoliton solutions are derived through the Hirota bilinear method and theirforms are rewritten in a compact way using Gram determinants. Veryinterestingly, we find that the presence of four-wave mixing effect induces abreathing vector soliton state in both the optical modes. Such breatherformation is not possible in the fundamental vector bright solitons of theManakov system. Then, for both strong and weak four-wave mixing effects, weshow that the nondegenerate solitons in the GCNLS system undergo, in general,novel shape changing collisions, in addition to shape preserving collisionunder suitable choice of wave numbers. Further, we analyze the degeneratesoliton collision induced novel shape changing property of nondegenerate vectorsoliton by deriving the partially nondegenerate two-soliton solution. Forcompleteness, the various collision scenarios related to the pure degeneratebright solitons are indicated. We believe that the results reported in thispaper will be useful in nonlinear optics for manipulating light by lightthrough collision.