IMPROVEMENT IN Q WITH LOW-FREQUENCY POLARIZATION MODULATION ON TRANSOCEANIC EDFA LINK

While polarization scrambling increases the Q seen over ultralong EDFA links, the improvement is limited by the generation of amplitude ripp le, which acts to reduce the mean and increase the fluctuations in Q. It is shown that by choosing a frequency close to the erbium dynamic g ain response cutoff, the a.m. is suppressed and a better Q improvement is obtained. This approach yielded a 1.7 dB increase in mean Q on a 6 300 km system, with a significant reduction in the standard deviation of the Q variations.