光纤色散相移监测方法的研究

【作者】 李纯丹；

【导师】 陈福深；

【作者基本信息】 电子科技大学 ， 光学工程， 2005， 硕士

【摘要】 随着社会的信息化,人们对信息的需求越来越大,这种需求直接推动了作为通信网主要传输方式的光纤传输朝着高速率、大容量和长距离的方向迅速发展。由于光纤放大器的出现,光纤损耗已不再是限制光纤传输距离的主要因素,色散逐渐引起了人们的重视。色散会引起数字光脉冲信号在传输中展宽,导致码间互扰(ISI),使系统误码率(BER)增加,从而限制了通信容量和通信距离的进一步增长。尤其是单波道速率为40Gbit/s 及以上的密集波分复用(DWDM)系统,对每个波道进行精确的动态色散补偿非常重要。光纤色散监测技术作为动态色散补偿的基础,大力开展这方面的研究更是重中之重。本文在对光纤色散特性研究的基础上,提出了通过监测单频音子双边带相对相移来实现实时色散监测的方法,并独立完成了监测公式的理论推导。接着讨论了监测信号与数字信号的相互影响,对监测信号的频率和幅度进行了优化设计。然后对光滤波器带宽、调制器啁啾、自相位调制(SPM)、交叉相位调制(XPM)、偏振模色散(PMD)、放大自发辐射(ASE)和四波混频(FWM)等因素对监测值的影响进行了理论计算和仿真分析。结果表明该方法的监测范围有限,只能用于未完全补偿的光纤系统中残留色散的监测。放大自发辐射和四波混频等因素的影响很小;光滤波器带宽、调制器啁啾和自相位调制的影响比较有规律,可以通过对监测公式的修正来改善;交叉相位调制和四波混频的影响较严重也较复杂。针对单音双边带相移监测方法监测范围有限的主要缺点,本文对监测方法进行了改进,提出了使用副载波监测音子的双边带相移监测方法,并进行了理论推导和仿真分析。结果表明,此方法很大地提高了色散的监测范围,而且通过改变监测音子的频率大小还可实现监测范围动态调整。但是,交叉相位调制和偏振模色散仍然是影响系统监测精度的主要因素,没有得到很好的改善。随着研究的深入,本文对系统结构作了进一步优化设计。理论推导和仿真分析证明,此结构不仅获得了理想的监测范围,而且简化了监测系统的结构、节约了成本的同时增强了监测系统的稳定性。系统受调制器啁啾、非线性效应和偏振模色散的影响也大大减小,监测精度有了相当的改善。本文提出了新颖的光纤色散监测方法,并进行了详细的理论推导和大量的仿真计算。本文的研究工作对提高系统传输容量,增加光纤传输距离,最终实现高性能的色散管理全光网络有着重要的理论和实践意义。更多还原

【Abstract】 With the informationization of the society, the demands for information aregreater and greater, which has directly promoted the development of fibercommunication towards high speed, large capacity and long distance rapidly for theoptic-fiber is the main transmission means of communication network. Since theappearance of optic-fiber amplifier, the attenuation is no longer the main factorrestrains the optic-fiber communication system from long distance transmission, thechromatic dispersion caused people’s attention gradually. The chromatic dispersionbroaden the wide of digital optical pulse as it transmits through the optic-fiber, causesthe inter-symbol interference, deteriorates the bit error rate, which limits thecommunication capacity and further growth of the communication distance.Especially in dense wavelength division multiplexing system with the channel bit-rateabove 40Gbit/s, it is very important to carry on accurate dynamic compensation forchromatic dispersion to every channel. The chromatic dispersion monitoringtechnology as foundation of dynamic compensation, it is the most important thing tolaunch more research in this field in an effective manner.Based on the deep research on the characteristic of chromatic dispersion, thispaper has proposed an initial chromatic dispersion monitoring method thoughdetecting the phase drift between the two sideband of pilot tone, and has finished thetheory calculation of the monitoring formula by oneself. Then has analyzed theinfluence between the pilot tone and the digital signal and has optimized thefrequency and amplitude of the pilot tone. In the latter segment of the third chapter,the influence of some factor such as the bandwidth of optical filter, chirp of themodulator, self phase modulation, cross-phase modulation, polarization modedispersion, amplified spontaneous emission and four wave mixing has been calculatedwith theory and simulated in emulator. The result indicates, the main disadvantage ofthis monitoring method is its limited range, the influence of amplified spontaneousemission and four wave mixing is negligible, the influence of optical filters’bandwidth, chirp of the modulator, self phase modulation is more regular, can beimproved by revising the monitoring formula, but the influence of cross-phasemodulation, polarization mode dispersion is relatively complicated.To overcome the main disadvantage of the monitoring method using a single pilot更多还原