DSP-based Logic Control Unit In Polarization Mode Dispersion Compensation Systems

The research work in this dissertation is supported by National 863 High Technology Important Project, No. 2001AA122041, "Technologies of Adaptive Compensation for Polarization Mode Dispersion", National Natural Science Foundation of China, No. 60577046, "The research on dynamically combining relaxed technology with compensation technology for Polarization Mode Dispersion Systems", and Corporate Building Project of Beijing Educational Committee No.XK100130537, "The research on some important technologies in high-speed optical fiber communication systems ".Polarization mode dispersion (PMD) is considered to be one of the main obstacles for long-haul optical fiber communication systems with the speed beyond 10Gb/s. Therefore, it has been a hot topic in recent years. The basic theory of PMD and PMD compensation method is discussed in this paper. And we systematically investigate the design and operating system of the logic control unit based on DSP. PMD compensation experiments and the transplant of PSO are completed successfully, using the logic control unit.Above all, the research work in the dissertation is summed up as following:1 The basic theory about PMD and the monitoring techniquesThe expressions about polarization light, the Jones transmission Matrix of polarization device are introduced, and the origin of PMD is discussed.The measurement techniques of PMD is reviewed. And three kinds of PMD monitoring techniques are especially discussed, including Degree of Polarization, DOP ellipsoid and the power of data's spectral frequency components.2 The design of logic control unit design based on DSP, for PMD compensation systemsThe basis of DSP technology and the general method for DSP system design are introduced.The configuration and capability of the current hardware unit for PMD compensation systems is analyzed and the collectivity scheme for the hardware system which is based on DSP is designed.The hardware system for logic control unit based on DSP is designed concentratively, including the minimum DSP system, A/D acquisition circuit design, D/A control circuit design and so on. And the system resource of DSP system is been taken on.3 The PMD compensation methods and the experiment using the logic control unit based on DSPTechniques to mitigate or to compensate PMD are reviewed and the compensation methods of the first order PMD and the second order PMD is introduced.More efforts are spent on the optical link system experiments for confirming the validity of the logic control unit based on DSP. PSO algorithm is introduced emphasizily. Combining with optical experiments, PSO algorithm is successfully migrated to the DSP system.The first-order and the second-order PMD compesation experiments are successfully completed using the logic control unit based on DSP. The results of the experiments show that the DSP system has the better performance in PMD compensation systems.