Research On Implementation And Improvement Of Algorithm Of Compensation Of Polarization Mode Dispersion And In Fiber Communication System

Due to the imperfectness of the optical fiber, outside stress, environment bi-reflectivity and etc, polarization mode dispersion (PMD) has become the main obstacle that limits the upgrading of bit rates and span of relay distance. Furthermore, the statistic property of PMD caused by external conditions and other reasons makes the PMD compensation extremely difficult. Thus, how to compensate for PMD has become the key problem in the optical fiber communication system both at home and abroad. This thesis mainly studies PMD compensation methods and the realization of an adaptive PMD compensator. Works that have been done in the thesis are listed:1 Every kind of PMD optical compensation schemes were completely studied, and the feedback compensation method using electrical power at certain frequency as the feedback signal was chosen with the present research conditions and the devices would be used in the experiment considered. The experiment of first order PMD adaptive compensation system, which provided the experimental basis for further improve the efficiency of the control algorithm, has been completed.2 Degree of Polarization (DOP) was studied theoretically as another feedback signal for PMD compensation system. The first order PMD adaptive compensation system has been finished with DOP as the feedback signal and the results were good. The whole control modular was transplanted to digital signal processor (DSP), which was good for getting rid of the dependence on the personal computer and made the PMD compensation system more practical.3 A novel adaptive PMD compensation algorithm, which successfully solved the problem of easily been trapped into local optima, efficiently eliminated the hysteresis of polarization controller (PC) was developed in the tracking course with no visible worsen of the feedback signal in the compensation process. The long term testing with multi-times disturbances showed that the response time for the compensator to recover from a sudden disturbance was at the level of millisecond.