High-speed Fiber-optic Communication Systems, Polarization Mode Dispersion Compensation

Fiber loss and dispersion always are the main obstacles in fiber optic communication. With the development of optical amplifiers and chromatic dispersion compensation technology, these obstacles 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. Further more, as the bit-rate of a single channel in optical fiber transmission approaches 40Gbit/s or beyond, the effect of the second order PMD can't be neglected. It makes the intersymbol interference and corrupts severely the performance of the system. Because of the impact of the circumstance, PMD shows statistical characterization. It makes the compensation of PMD become difficult and PMD was considered the final factor of the optical communication.First, a summary of the relating concepts of PMD and its statistics nature was given in chapter 2, which are the fundamentals for farther discussion. Second, in chapter 3, an expression of PMD-induced pulse broadening was derived based on principal state polarization (PSP), which is the description for first-order PMD; then discussed the deterioration of receiver's sensitivity caused by PMD and the effect of PMD on RF spectrum at the receiver; the experimental result was given for the later.The focus topic of this thesis is the PMD compensation (PMDC) technology. In chapter 4, we first presented the principle of first-order PMDC and a general model of PMDC; then described each sub-model, respectively, and gave a summary and comparison of present main PMD compensation or mitigation methods; PMDC inWDM and soliton system were also discussed at last. In chapter 5, for compensating polarization mode dispersion (PMD) in a high speed optic communication system, a planar lightwave circuit (PLC) equalizer, based on the minimum mean square error control criterion, is proposed. The system performances of being compensated and not being compensated are compared, and the compensating performance of a series of PLC equalizers is analyzed. Further more , this thesis improves the b factor that can describe the pulse broadening . It isdemonstrated that the PLC equalizer can decrease the optical pulse broadening and reduce the bit rate error(BER).