光纤中5阶非线性效应对光脉冲传输的影响

The effect of quintic nonlinearity on the propagation of optical pulse in optical fibers

为了研究5阶非线性效应对光脉冲在光纤中传输的影响,采用分步傅里叶算法数值求解了含5阶非线性项的扩展非线性薛定谔方程,并进行了理论分析和数值模拟。计算结果显示,负的5阶非线性效应使光脉冲峰值减小,脉冲展宽,正的5阶非线性效应使峰值增大,脉冲被压缩。较小的5阶非线性效应产生较小的调制不稳定性,因而光脉冲能保持基本的形状,忽略光纤的损耗时,光脉冲保持绝热传输。对正的5阶非线性效应,适当小的损耗可以减缓调制是不稳定性。结果表明,在5阶非线性系数固定的情况下,初始入射脉冲的峰值会显著地增加5阶非线性项的贡献。

In order to study the effect of quintic nonlinearity on the optical pulse propagating in the optical fiber, the extended nonlinear Schrodinger equation, including the quintic nonlinearity, was solved by means of split-step Fourier transform. The results showed that the negative quintic nonlinearity stretched the pulse while the positive one compressed the pulse width. Less quintic nonlinearity produced less modulation instability of the optical pulse, thus the optical pulse almost maintained the pulse envelope. While the absorbed coefficient was neglected, the propagation of the pulse was adiabatic. For the positive quintic nonlinearity, some proper absorbed coefficient could slow down the modulation instability. If the quintic nonlinear coefficient were fixed, the effect of quintic nonlinearity would be more obvious when the input peak power of the pulse increased.