Investigation Of Dispersion Monitoring Technology For Ultra-High Speed Optical Transmission Link

With the development of ultra high speed, ultra long haul, and ultra large capacity forthe optical transmission system, fiber chromatic dispersion effects on the transmissionsystem is growing. Chromatic dispersion (CD) tolerance receded rapidly along with datarate upgrade, for the same modulation format of optical transmission systems, thedispersion tolerance for100Gbit/s system is only1%of that for10Gbit/s system. Thisrequires a high accuracy of compensation for the transmission fiber dispersion. For the sakeof realizing in line CD management effectively and accurately in high speed opticaltransmission system, it’s necessary to monitor the performance of optical transmission links,the monitoring result can be regarded as reference of chromatic dispersion compensation. Inthis paper, we analyzed existing optical performance monitoring (OPM) technology andproposed a novel method of OPM for all optical transmission links, this method has severaladvantages: flexible operation, wide spectral range, fast speed and good accurate, both CDand PMD can be monitored. We analyzes theoretically based on the proposed method, andconfirm the feasibility of the method by making simulation and experiment.Firstly, this thesis, the physical damage to the fiber is theoretically analyzed, includingCD, PMD and signal attenuation effects, giving their impacts on the transmission systemperformance. This provides a theoretical basis for in depth study and discussion in thesubsequent chapters.Secondly, for the existing high speed optical transmission links, the influence of CDon optical signal phase is analyzed in depth, and finding a reaction mechanism between CDand receiving signal power, spectrum phase. Based on the analyzed results, there are threemethods for CD monitoring are proposed in this thesis, we analyze theoretically and buildmathematical model for each method, make principle verification through simulation andexperiment. Several optical transmission systems (et.10G NRZ,40G NRZ,40G RZ,40GDPSK,100G RZ DQPSK) are considered in each method verification, the results ofverification indicated that the method based on single sideband phase difference detection(SSB PDD) technology not only can monitor CD of fiber links, but also can distinguish CDpolarity. Besides, the operation of proposed two methods of CD monitoring is independent of data rate and modulation format, two methods provide a powerful technical support toin line dispersion management.Thirdly, for the existing four methods of PMD monitoring technology, we make a deepinvestigation and study, and elaborate pluses and minuses of each method. In this chaper,we propose a novel method of PMD monitoring based on CD monitoring technology,mathematical model of the method is built in accordance with monitoring principle. Theresults of verification indicated that the method based on single sideband fast slow axisphase difference detection (SSB FSPD) technology can realize dynamic PMD monitoringthat includes differential group delay (DGD) and polarization state of output light. Theoperation of proposed PMD monitor method is also independent of data rate andmodulation format.Finally, we investigate the impact of CD on PMD monitoring, simulation resultsshows that the PMD monitoring based on SSB FSPD technology is independent of linkdispersion. Besides, we also simulate PMD monitoring in various optical system, include10G NRZ、40G NRZ、40G RZ、100G RZ DQPSK modulation format links, the resultsdemonstrate that the link dispersion has no effect on PMD monitoring for all modulationformat links.