Optimization Scheme For Second-order PMD Compensation

As the bit rate of a single channel in an optical transmission system increases, polarization mode dispersion (PMD) impairs the transmission performance more severely and the first-order approximation of the PMD vector becomes less valid. Compensation for higher-order PMD effects is one of the key issues to be addressed in the deployment of high-data-rate long-haul optical transmission systems. To accomplish second-order PMD compensation, there are two main problems. First, what the structure of the PMD compensator and the required number of the control parameters are. Secondly, how to optimize the control parameters.This thesis is part of "The research on multi-funtion polarization mode compensator", the project 60377015 supported by National Nature Science Foundation of China. we have researched on the structures and the compensation principles of the compensators, the global optimization problem of the control parameters in the compensator. The main work in this thesis is as follows: reviewed the basic theory of polarization, which included the basic concept of polarized light, the model of the principal states of polarization, the polarization vector and higher-order polarization mode dispersion, and the concatenation rule of PMD. summarized the structures and the principles of the first-order, second-order and complete second-order compensators respectively, and then described mathematically the problem of PMD compensation as a global optimization problem. introduced the DIRECT algorithm into the field of PMD compensation and for the first time advanced the combination of the DIRECT algorithm and the Hooke & Jeeves algorithm as the optimization scheme for PMD compensators, which can complish the tasks of searching for the initial global optimal solution of the control parameters and then tracking the global optimal solution. developed the C programmes of the algorithms independently, modified the Hartman 6 function, used the returning values of the function to simulate the degree of polarization (DOP), numerically simulated the optimization process of the control parameters, and validated the optimization scheme. applided the the optimization scheme to the PMD compensation experiment.