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稳定性是影响Fermi-Pasta-Ulam-Tsingou(FPUT)现象实验观测的一个十分重要的因素, 针对文献中FPUT现象稳定性分析贫乏的问题, 本文主要通过数值模拟方法研究非线性光纤中影响FPUT现象稳定性的主要因素. 本文采用的初始条件为实验上比较容易实现的正弦扰动平面波加上白色噪声, 发现增加扰动振幅及扰动信号与泵浦光之间的相位差均可极大程度的影响FPUT现象的稳定性. 结果表明: 1) 当扰动振幅从零逐渐增加时, 所观察到的FPUT现象的稳定性逐渐增强; 当扰动振幅增加至临界值, FPUT现象的稳定性增至最强; 当扰动振幅大于该临界值, FPUT现象的稳定性开始逐渐减弱. 2) 当扰动频率位于传统调制不稳定性区域时, 随着扰动信号与泵浦光之间相位差从0增加至π/2, FPUT现象的稳定性先减弱, 当相位差增加至某临界值, FPUT现象的稳定性减至最弱, 当相位差大于临界值, FPUT现象的稳定性又出现逐步增强的规律. 当扰动频率位于非传统调制不稳定性区域时, 与传统情况不同, FPUT现象的稳定性随扰动信号与泵浦光之间的相位差的增加而增强. 以上结果表明, 在FPUT现象的实验中, 为观察到更稳定的FPUT现象, 扰动振幅的值不能太小, 且扰动信号与泵浦光之间相位差也要适宜. Stability plays a significant role in successfully observing Fermi-Pasta-Ulam-Tsingou (FPUT) phenomenon in experiment. However, there are few relevant studies in the literature. The primary object of this work is to study the stability of FPUT phenomenon in the nonlinear fibers numerically. In this study, we take the sinusoidally perturbed continuous waves (CWs) with white noise as the imposed initial condition, which can be readily realized in real experiments. We find that both the perturbation amplitude and phase difference between the perturbation and pump can drastically affect the stability of the resulting FPUT phenomenon. Firstly, as the perturbation amplitude increases, the FPUT phenomenon becomes much more stable. When the perturbation amplitude reaches a critical value, the most stable FPUT phenomenon can be observed. With the further increase of the perturbation amplitude, the stability of the resulting FPUT phenomenon weakens. Secondly, the phase difference between the perturbation and pump takes distinct effects on the stability of FPUT phenomenon for perturbation frequency located inside and outside the conventional modulation instability (MI) band. For the perturbation frequency located inside the conventional MI band, as the phase difference between the perturbation and pump increases from zero, the corresponding FPUT phenomenon first is less stable, and then becomes most instable at a critical phase difference; after that, the stability of the FPUT phenomenon is enhanced again. For the perturbation frequency located outside the conventional MI band, the stability of FPUT phenomenon is enhanced monotonically as the phase difference increases from 0 to π/2. In order to observe a much more stable FPUT phenomenon, as shown in the above results, the perturbation amplitude should be moderately large, and the phase difference between the perturbation and the pump should be appropriate to avoid the most instable FPUT phenomenon. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] -
[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35]
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