Duan Liang, Zhao Li-Chen, Xu Wen-Hao, Liu Chong, Yang Zhan-Ying, Yang Wen-Li
School of Physics, Northwest University, 710069 Xi'an, China.
Shaanxi Key Laboratory for Theoretical Physics Frontiers, 710069 Xi'an, China.
Phys Rev E. 2017 Apr;95(4-1):042212. doi: 10.1103/PhysRevE.95.042212. Epub 2017 Apr 19.
We study the correspondence between modulational instability and types of fundamental nonlinear excitation in a nonlinear fiber with both third-order and fourth-order effects. Some soliton excitations are obtained in the modulational instability regime which have not been found in nonlinear fibers with second-order effects and third-order effects. Explicit analysis suggests that the existence of solitons is related to the modulation stability circle in the modulation instability regime, and they just exist in the modulational instability regime outside of the modulational stability circle. It should be emphasized that the solitons exist only with two special profiles on a continuous-wave background at a certain frequency. The evolution stability of the solitons is tested numerically by adding some noise to initial states, which indicates that they are robust against perturbations even in the modulation instability regime. Further analysis indicates that solitons in the modulational instability regime are caused by fourth-order effects.
我们研究了具有三阶和四阶效应的非线性光纤中调制不稳定性与基本非线性激发类型之间的对应关系。在调制不稳定性区域中获得了一些孤子激发，这些孤子在具有二阶和三阶效应的非线性光纤中尚未被发现。明确的分析表明，孤子的存在与调制不稳定性区域中的调制稳定性圆有关，并且它们仅存在于调制稳定性圆之外的调制不稳定性区域中。应当强调的是，孤子仅在特定频率的连续波背景下以两种特殊的轮廓存在。通过向初始状态添加一些噪声对孤子的演化稳定性进行了数值测试，这表明即使在调制不稳定性区域中，它们对微扰也具有鲁棒性。进一步的分析表明，调制不稳定性区域中的孤子是由四阶效应引起的。
