Research On The Soliton Solutions And Their Transmission Characteristics Of The Vector Dispersion-managed System

When the group velocity dispersion and self-phase modulation effect are balanced in the optical fiber systems,optical solitons can keep their shape and speed unchanged for long-distance transmission.Therefore,the potential applications of optical solitons,such as optical communication systems and all-optical ultrafast switching devices,have become a research hotspot.The bright and dark soliton solutions of the nonlinear Schr?dinger equation with variable coefficients have been reported for a long time.Based on these solutions,the effects of high-order dispersion,self-steepening and self-frequency shift on bright and dark soliton solutions have been studied successively.However,there are relatively few studies on the multi-soliton solutions of multi-component coupled nonlinear Schrodinger equation and their interactions between multi-solitons.In this paper,based on the Hirota bilinear method,we firstly study the multi-component coupled nonlinear Schr?dinger equation with variable coefficients,and obtained the mixed 3-soliton solution.In order to better understand the properties of solitons interaction,the asymptotic analysis is carried out.Finally,we study the interactions between solitons numerically.The results show that when the eigenvalues are different,the 3-soliton solutions can be presented as regular solitons,bounded solitons,or the combination of them.The regular bright solitons and bounded bright solitons can interact elastically or inelastically by adjusting the parameters to satisfy some certain conditions,while the dark solitons only reveal elastic interactions.But for the combination of regular solitons and bounded solitons,the interacting rules of the bright soliton components are very complex and influenced by parameters except that the dark soliton components still maintain the elastic interactions.Then,based on the modified nonlinear Schr?dinger equation(Vc-MNLSE),which includes distributed dispersion,self-phase modulationand self-steep coefficients,the influence of different forms of Raman gain on the transmission characteristics of dark soliton solutions are discussed detailedly by using the split-step fourier transform method.The results show that the Raman gain of the periodic sine function causes the background wave periodically oscillating of the two dark soliton solutions.And the oscillation period and amplitude vary with the parameters of the sinusoidal function.The Raman gain of the hyperbolic sinusoidal function and exponential function will increase the background wave power of the two dark soliton solutions.The Raman gain of tangent function will make the background waves of two dark soliton solutions change step by step and the periodic oscillation dark soliton solutions will split in the transmission process.