Polarization effects in a single mode optical transmission link

Polarization dispersion is an effect which may cause data rate penalty in optical links. This is caused by the combined effect of fibre birefringence and polarization couplings due to environmental perturbations. Polarization dispersion is therefore a stochastic quantity and results in a fluctuating pulse broadening, making only an expectation value to be forecast. In practical systems this dispersion can be neither avoided nor cancelled. The different methods for polarization dispersion measurements reported to date are described. Details of the experimental set-up and results are shown for the interferometric loop technique, which easily enables the polarization dispersion expectation value to be measured using a particularly simple set-up