二阶光纤孤子传输特性研究

【作者】 杨懿；

【导师】 曹文华；

【作者基本信息】 五邑大学 ， 信号与信息处理， 2008， 硕士

【摘要】 对于光纤孤子的相互作用问题,现有的研究主要集中于基阶孤子间相互作用,而针对高阶孤子间相互作用问题的研究相对较少。本文通过分步傅立叶方法进行数值计算,研究了二阶光孤子在光纤中的传输特性,在总结前人研究成果的基础上得出了一些有益的结论。在色散位移光纤中,研究了三阶色散影响下,同相和反相二阶孤子之间的互作用,分析了同相和反相二阶孤子对衰变后时域波形和频域频移的变化,发现三阶色散使二阶孤子分裂出一大一小两个不同振幅的基阶孤子,并彼此分离,但孤子对中心频率频移量却减小。通过引入非线性增益控制可以有效抑制二阶孤子间互作用,使孤子保型传输而不发生衰变,但孤子对会偏离原来的时间槽。这种偏离主要是由于三阶色散的影响造成的。因此我们提出周期性改变三阶色散系数的方法,减小了三阶色散的不利影响,抑制了孤子中心频率的频移。时域相位共轭技术(TPC)能够对群速度色散,自相位调制,脉冲内拉曼散射等效应进行补偿。但是当脉冲宽度较小,或者脉冲中心波长接近零散射波长时,三阶色散效应变得不可忽略。TPC由于无法补偿三阶色散,因此限制了其进一步的应用。在总结前人解析方法的基础上,因此我们提出了一种谱共轭技术(SPC)。它通过在传输距离的中点在频域对脉冲进行共轭变换,即可实现在传输距离的后半程对各阶色散,自相位调制,自陡效应的补偿。将SPC与非线性增益控制结合作用于二阶孤子脉冲序列,获得了较好的整形效果。更多还原

【Abstract】 For the issue of the interaction of optical solitons, there have been many studies focusing on the interaction of fundamental solitons, but few is on the interaction of higher-order solitions. In this paper, the propagation of two neighboring second-order solitons in single-mode fiber is investigated with Split-step Fourier Algorithm. On the basis of summarizing the reported research results, some useful results were obtained.Under the influence of third-order dispersion, the interaction of second order solitons in dispersion-shifted fibers is investigated numerically. The characteristics of second order solitions split is studied in the time and frequency domain. It is found that under the influence of third-order dispersion, tow second order solitons are both split and apart from each other. But the frequency shift is decreased. A nonlinear gain and periodical alternation of third-order dispersion can be used to effectively suppress soliton interactions and the effects of third-order dispersion, and stabilize the soliton propagation.Temporal phase conjugation(TPC) was proposed to compensate for group-velocity dispersion, self-phase modulation, and intrapulse Raman scattering of an optical pulse. However, when the pulse width is sufficiently short or the center wavelength is near the zero-dispersion point, third-order dispersion becomes more prominent and limits the reshaping performance of TPC. We propose to use a spectral phase conjugation(SPC) method that conjugations of the optical pulse in the frequency domain. With this method dispersion of all orders, self-phase modulation, and self-steepening in a fiber are automatically compensated. A hybrid scheme combining SPC and nonlinear gain can offer superior performance.更多还原