Operation of digital optical transmission system with minimaldegradation due to polarisation mode dispersion

The probability of BER degradation above 10^-9 is evaluated theoretically as the quality parameter for examining the robustness of an optical transmission system incorporating an EDFA to fibre polarisation mode distortion (PMD). Provided that there is an existing power margin, a significantly reduced sensitivity to PMD is achieved by detuning the decision level of the optical receiver from the optimum for zero PMD