Based On Liquid Crystal Polarization Mode Dispersion Compensation

When the transmission bit-rate can get to 10Gbit/s and above,research show that Polarization Mode Dispersion(PMD) ignored formerly can damage the performance of system and limit the transmission bit-rate and length of system. So PMD turns into the focus of research of Optical Fiber Communication system in the world.PMD in fiber is formed for the incomplete structure and the action of external stress on optical fiber and is a stochastic variable of Maxwell distribution. This Paper formulates the PMD generally. Based on the basic concepts of PMD, the basic theories of PMD was summarized , the PSP(Principle state of polarization) model, the measurement techniques, and the influence of PMD on optical fiber communication system is also described .The coupled nonlinear Schrodinger equation is solved by means of Maxwell field equations, and the influence of PMD on transmission system may be numerically calculated by changing parameters of pulse.The focus topic of this thesis is the PMD compensation(PMDC) technology. The thesis presented the principal 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.Based on the elastic continuum theory and the common concept of liquid crystal, the detailed formulas for calculating the distribution of LC directors under an applied voltage are given. The light transmission in liquid crystal are also theoretically analyzed.In this dissertation, the retardation of liquid crystal are studied to restraining PMD, and variable retardation of liquid crystal and endless polarization control algorithm using adjustable linear retarders of liquid crystal are also described in detail. Finally, a theory and systematic simulation of liquid-crystal modulator arrays of compensator has been worked out.