色散管理孤子系统的调制不稳定性

摘要

为了探究色散管理孤子系统抗微小扰动的能力,从色散管理孤子的调制不稳定性出发,利用孤子传输满足的非线性薛定谔方程,采用线性稳定性分析和数值模拟,得到色散管理系统中调制不稳定性的增益谱;得出色散管理孤子各阶调制不稳定性的增益曲线,并分析了基阶调制不稳定性起主导作用的条件,讨论了色散图中路径平均色散值.结果表明,色散深度对基阶调制不稳定性增益谱有影响,在平均色散为负值的情况下,平均色散值βav(βav＜0)越大,色散波动幅度越小,基阶调制不稳定性的增益越小,更有利于抑制调制不稳定性增益;但将平均色散值降至更小时,调制不稳定性增益谱不再连续.%In order to explore the ability for a dispersion managed soliton (DMS) system to resist smaller fluctuation, firstly, starting from the analysis of its modulation instability ( MI), on the base of nonlinear soliton transfer equation, the expression for the gain spectrum of MI in DMS was deduced. Secondly, the gain curve of each order MI was presented, and then conditions of the fundamental MI playing a leading role were analyzed. Finally, the influence of average dispersion and dispersion depth on MI was discussed. The results show that in negative average dispersion region as the average dispersion becomes larger and dispersion fluctuates smaller, and influence of fundamental MI becomes smaller, so it is more favorable to suppress MI. However, MI gain spectrum appears side-lobe phenomenon, when the average dispersion becomes very small.