拉曼增益和自陡峭效应对艾里脉冲传输特性的影响

利用包含拉曼增益和自陡峭效应的非线性薛定谔方程, 忽略光纤损耗的情况下, 模拟和分析了艾里脉冲在单模光纤中的传输特性. 发现艾里脉冲在光纤中传输时由于受到拉曼增益和自陡峭效应的影响, 在一定条件下会转变为孤子, 并且, 转变后形成的孤子传播方向发生了偏移. 在时域方面, 艾里脉冲的小峰个数迅速减少, 变成含有一个主峰和次峰能量可以忽略的峰值结构, 此时, 可以把这个峰值结构近似为孤子的结构. 同时发现, 不管截止系数a和艾里函数振幅b 取什么值, 拉曼增益和自陡峭效应都会减小艾里脉冲的时移. 研究了艾里脉冲的加速度特性, 发现一定的传输距离下, 艾里脉冲的横向加速度在初始时并不是一个稳定的值, 但随着传输距离的增大, 加速度慢慢趋于稳定.

Influences of Raman gain and self-steepening on the propagation characteristic of Airy pulse

By using nonlinear Schrödinger equation including Raman gain and self-steepening but ignoring fiber loss situation, the propagation characteristics of Airy pulse are simulated and analyzed in the single-mode fiber. Simulations show that Airy pulse can be converted into soliton and its propagation direction is skewed due to the effects of Raman gain and self-steepening under a certain condition. In time domain, the number of small peaks of Airy pulse reduces rapidly. Airy pulse becomes a peak structure containing a main peak and sub-peaks where the energies can be ignored by changing the coefficient a reasonablely, which is approximated as the soliton structure. Therefore, Airy pulse is regarded as transforming into soliton. Meanwhile, in the case of small values b, there exists a significant difference in shape between Airy pulse and soliton. With the value of parameter b increasing slowly, the shape of Airy pulse is very close to soliton's, therefore Airy pulse can transform into soliton by changing value b reasonablely. Compared with by changing b value, Airy pulse convered into the soliton is stable by changing the a value reasonablely. Simultaneously, with the increases of values of coefficient a and amplitude b, the time-shift of Airy pulse increases. However, the time-shift of Airy pulse would decrease when Raman gain and Self-steepening become strong, no matter what the values of a and b are. Further, the acceleration properties of Airy pulse are investigated. It is found that Airy pulse autoacceleration is not a stable value at the beginning but it gradually stabilizes with the increase of transmission distance. The reason is that the energies of secondary peaks exert a tremendous influence on the main lobe of Airy pulse at the beginning, however, secondary peaks diffuse fast with the increase of transmission and then the influence can be ignored to a certain extent. So, the main peak gradually stabilizes with the increase of transmission distance.