Polarization-Mode Disperion in Optical Fibers: Characterization, Transmission Impairments, and Compensation

Doktorsavhandling, 2001

The topic of this thesis is polarization-mode dispersion (PMD) in optical fibers and its impact on high-speed data transmission. The work can be divided into three parts which deal with the major aspects of PMD: characterization, transmission properties and compensation. Different methods have been developed for measurement of how the PMD is distributed or accumulated in long fiber cables. As the methods are particularly useful for identifying subsections with large PMD they could facilitate substantial improvements of poor links. The impact of PMD in transmission systems has also been investigated. In particular, we have quantified the benefit of applying a polarization interleaving scheme, which is a well known technique for suppression of nonlinear crosstalk in wavelength division multiplexed (WDM) systems. The effect of using solitons has also been experimentally quantified in both conventional and dispersion-managed, PMD-distorted systems. The results show that solitons are more robust to PMD than linear pulses and that dispersion-managed solitons can be even more robust than conventional solitons. Also the sensitivity to PMD for different data formats was investigated by means of numerical simulations. PMD-compensation is currently an intense research field. We present exact analytical expressions for the expected broadening of pulses affected by PMD. The theory also describes the benefit of using different optical PMD-compensation techniques. Also, by means of numerical simulations, we quantify the advantage of using various compensation techniques.