INTERACTIONS AND OSCILLATIONS OF THREE-SOLITON SOLUTION IN THE VARIABLE-COEFFICIENT KUNDU-ECKHAUS EQUATION FOR DISPERSION MANAGEMENT SYSTEMS

In dispersion management systems, the communication quality can be affected by soliton interactions and oscillations. In this paper, the variable coefficient Kundu-Eckhaus equation, which describes the propagation of femtosecond optical solitons in optical fibers, is investigated to control interactions and oscillations of solitons. The analytic three-soliton solutions for this equation are obtained by using the Hirota direct method. The different characteristics of soliton interactions and oscillations are presented when the group-velocity dispersion (GVD) and nonlinearity vary with the normalized propagation distance x. If the GVD coefficient r(x) and the nonlinearity m(x) are taken as the same arc-hyperbolic sine function, the interaction between parabolic-type solitons can be weakened by adequately choosing the corresponding free parameters of the model. When r(x) and m(x) are chosen as the same trigonometric sine function, the problem of how to control the interaction between parallel solitons with varying oscillation period or intensity is investigated. Moreover, the soliton phase shift can be adjusted to control soliton interactions. The obtained analytical and numerical results may help the design of optical communications systems through studying the complex soliton interactions.