Measurement and control of the state of polarization of light in optical fibers

High speed fiber optic networks running at or more than 10 Giga-bit per second need polarization compensation system to overcome the impairment caused by the birefringence effect in the single mode fibers. This dissertation studies polarimeter, polarization controller and polarization compensation algorithms that are three key components of the polarization compensation system.; The dissertation propose a novel polarimeter design that is based on Brewster law. The polarimeter has characteristics of in-line, real-time and preserving state of polarization. It can be easily calibrated by the procedure discussed in the dissertation. A prototype polarimeter system is designed and constructed which has been used in a experimental polarization compensation system successfully.; The detailed theoretical analysis of the effects of fiber squeezer based polarization controller in single and cascaded configurations is carried out in the dissertation. A novel idea of single position multiple squeezer polarization controller is proposed, which can provide continuous, endless and reset-free control of the polarization in the single mode fibers. The controller transforms the polarization state in the fiber by controlling the eccentricity and orientation of the fiber. Formulas are given to drive the individual squeezers.; In the dissertation we propose and develop a polarization compensation system that is capable of transforming and locking any polarization state into a circular polarization. The system monitors the two Stokes parameter s₁ and s₂ and uses PID based closed-loop feedback control algorithm to bring and maintain s₁ = 0 and s₂ = 0. The design makes it possible to develop low cost polarization compensators using simple electronic circuits. The polarization compensator based on this design can find potential applications in compensating polarization dependent loss or gain of fiber optic components and pre compensation module of the polarization mode dispersion compensation.