具有高阶耦合色散系数双芯非线性光纤耦合器开关的数值分析

基于耦合非线性薛定谔方程(NLSE),利用分裂步长傅里叶方法(SSFM),研究了具有高阶耦合色散系数时,双芯非线性光纤耦合器中的传输和开关特性.模型中,一阶耦合色散系数的存在类似于群速度失配,二阶耦合色散系数类似于群速度色散,并且会对另一个纤芯中的信号产生线性互调制.研究表明当一阶耦合色散系数较小时,光脉冲仍能在二纤芯之间周期性耦合传输,并且表现出良好的开关特性,当一阶耦合色散系数增大时,脉冲耦合传输的周期性和陡峭的开关特性遭到破坏,光脉冲在传输中发生分裂;二阶耦合色散系数使耦合器的耦合长度减短,开关阈值功率增加,开关特性也变得更加陡峭.

Numerical Study of Soliton Switching in Two-Core Nonlinear Fiber Coupler with High Order Coupling Dispersion Coefficient

Based on coupled nonlinear Schrodinger equation(NLSE)and the split-step Fourier method(SSFM),a numerical investigation of the propagation and the switching of fundamental solitons in two-core fiber nonlinear directional coupler(NLDC)with high order coupling dispersion coefficient is present.In this model,the first coupling dispersion is similar to the group velocity mismatch.The second coupling dispersion is similar to the group velocity dispersion(GVD),and it leads to mutual modulation for the other channel.Optical pulses propagate periodically inside fiber coupler and NLDC have sharp switching characteristics when the first order coupling dispersion coefficient is smaller,but the periodicity of the coupling transmission of optical solitons and the sharpness of switching were destroyed by the increase of the first order coupling dispersion coefficient,so optical pulses breakup in the propagation.The second order coupling dispersion coefficient reduce the coupling length,and increase the switching threshold power,as well as make switching characteristics become sharper.