【作者】 马慧；

【导师】 徐建波；

【作者基本信息】 山东师范大学 ， 光学， 2005， 硕士

【摘要】 随着传输容量的增大,以及传输速率的进一步提高,传统的线性系统由于色散和非线性效应的影响,已不能够满足当今通信的需要。光孤子是光纤色散和非线性相互作用的产物。光孤子通信技术是一种非线性全光长距离通信,它利用强脉冲在光纤中产生的非线性压缩来补偿脉冲的色散展宽,实现高速孤子脉冲的稳定传输。普通的光纤通信必须每隔几十公里就设一个中继站,对信号进行整形、放大、检查误码、再发射。但是用孤子的光纤通信就可以不用中继站。只要对光纤损耗进行增益,即可把光信号无畸变的传输极远的距离。光孤子是经过长距离传输而保持形状不变的光脉冲。一束光脉冲包含许多不同的频率成分,频率不同,在介质中的传播速度也不同,因此,光脉冲在光纤中将发生色散,使得脉宽变宽。但当具有高强度的极窄单色光脉冲入射到光纤中时,将产生克尔效应,即介质的折射率随光强度而变化,由此导致在光脉冲中产生自相位调制,使脉冲前沿产生的相位变化引起频率降低,脉冲后沿产生的相位变化引起频率升高,于是脉冲前沿比其后沿传播得慢,从而使脉宽变窄。当脉冲具有适当的幅度时,以上两种作用可以恰好抵消,则脉冲可以保持波形稳定不变地在光纤中传输,即形成了光孤子,也称为基阶光孤子。若脉冲幅度继续增大时,变窄效应将超过变宽效应,则形成高阶光孤子,它在光纤中传输的脉冲形状将发生连续变化,首先压缩变窄,然后分裂,在特定距离处脉冲周期性地复原。光孤子,特别是基阶光孤子使脉冲可以保持波形稳定不变的在光纤中传输的特性,自然使人们联想到它在通信领域的应用前景。本文运用拉格朗日变分法讨论了两个孤子的参量随传输距离的变化关系,较之常用的逆散射方法,计算过程更加简洁,并有良好的精度;利用分步傅里叶方法对非线性薛定谔方程进行数值求解;讨论了在等幅同相孤子注入,等幅异相孤子注入以及异幅同相孤子注入的情况下孤子的演化情况,得到了其数值解;最后分析了损耗和三阶色散对孤子传输的影响。本文共分为四部分:第一章介绍了光孤子的发现和作为通信系统的载体的优点,更多还原

【Abstract】 With the increase of the propagation capability and more improvement of thetransmission velocity, traditional linear system can not satisfy the needs of communicationbecause of the effect of dispersion and nonlinearity today. Optical soliton is the result ofinteraction between dispersion and nonlinearity. The technology of optical-solitoncommunication is the long distance communication, and it becomes the preferable schemeof new generation of the rapid velocity and long distance. It accomplishes stabilitytransmission by what strong pulse products nonlinear suppression compensating broadeningof pulse-dispersion in optical fiber. Normal optical-fiber must build a relay station to reform,amplify, and check mistaken code. Then signal will be emitted again. But communicationof the soliton do not use relay station. Only fiber loss gained, signal will be transmitted verylong without deformation.When narrower unicolour pulse with high intensity is poured into fiber, there is a Kerreffect, i.e., the refraction coefficient of medium varies with intensity. Self-phase modulationis caused in the optical pulse, so the variation of phase leads to frequency discerase in frontedge of the pulse; the variation of phase leads to frequency increase in back edge of thepulse. Thus the velocity of front edge is more slowly than back edge, pulse width isnarrowed. If the amplitude of the pulse is properly modulated, the above-effect iscompensated. So pulse is transmitted without deformation, i.e. optical soliton is emerged,named as low-order solitom. When the modulation of the amplitude is continually increased,the effect of narrow is over of above broadeness, and it comes into being high-order opticalsoliton. High-order optical soliton gives rise to change continuously, first narrow down,then split in the some distance periodly restoration. Because optical soliton especiallylow-order solitom can propagate with stability, it is naturally connected with the practicalprospects in the communication system.This paper discusses that parameters of two solitons varies with propagation distance更多还原