Polarization Mode Dispersion Compensation In High Speed Optical Communication Systems

With the development of optic amplifiers and chromatic dispersion compensation technology, fiber loss and dispersion have been overcome greatly. In this case, the influence of the polarization mode dispersion (PMD) becomes outstanding especially in high speed and long distance optical communication system. Futher more, as the bit-rate of a single channel in optical fiber transmission approaches 40Gbit/ps or above, the effect of the PMD can't be neglected . it corrupts severely the performance of the system and limit the transmission bit-rate and length of system. So PMD has also been a hot topic in optical fiber communication fields at these years. However, it is very difficult to compensate the PMD effect because of its stochastic feature. And it demands adaptive compensation and thus makes it difficult for PMD compensation.Firstly, a summary of the principle of PMD and its statistics nature was given in this paper, which include its definition, cause of formation, statistical distribution,representation, principal state of polarization (PSP) and cascaded vectors was introduced.,which are the fundamentals for further discussion in later chapters. Then the testing methods of polarization mode dispersion are analyzed in detail. These methods are the Interferometric Method, the Wavelength Scanning Method, the Jones Matrix Eigen-analysis Method and the Poincare Sphere Method. Later the compensation research the compensation means from optical and electricity, while investigating especial optical apparatus for limiting the PMD effect, and then the excellent and shortcoming between them was compared。Because of statistics nature of PMD it is necessary to design a PMD emulator in our research.So in the following we study the statistical characteristics of the first and second order PMD of a PMD emulator based on the Jones matrix of optical fiber and Monte Carlo method. The simulation results will be helpful for PMD emulator design. The focus topic of this thesis is the PMD compensation (PMDC) technology. We first presented the principle of first-order and two-order PMDC and a general model of PMDC; then described each sub一modal, respectively, and gave a comparison and discuss of a two-order PMD compensator in detail, Finally, we discussed the improvement of two-order PMDC: three-stage higher order PMDC scheme. Theoretical analysis shows that it is capable of compensating first-order and two-order PMD at the same time. And discussed the operating points,the control algorithms and the compensation methods in the PMDC in detail.