Two occurrence modes of large instantaneous DGD, observed in long term PMD field measurement in Indiana

Abstract

Through long-term field measurement, two occurrence modes of large instantaneous DGDs, less than 10 -5 probability, were observed. Most high DGD occurrences would be predictable, as the dominant case clearly shows positive correlation with ambient temperature. IntroductionRecent new transmission schemes have successfully increased its PMD tolerance significantly [e.g. 1], even if polarization mode dispersion (PMD) is difficult to handle due to its statistical behaviors caused by environmental influence. Beyond the PMD limitation overcome, the phenomenon still gives us more severe conditions (high instantaneous DGD) with very low probability less than 10 -5 . Usually, these rare events are allowed because the happenings are less than 6 minutes per year. However, as the duration is for all bandwidth at the same time, it may occur in limited bandwidth (for a few channels) with more than a few hours, practically. To prepare for the degraded conditions, it is important to grasp causes of very high instantaneous DGD amount.As reported [2, 3, 4], we had proceeded long term field fiber PMD measurements in Indiana. Those measurements gave us new insights of PMD phenomena such as wavelength dependency, positive and negative correlation with temperature, and so on. At the same time, huge numbers of data more than 70 million in the continuous measurements made us analyze the data points of the rare events.In this study, we investigated very low probability events less than 10 -5 with higher instantaneous DGD values. There are two types of events occurrence modes and the dominant case could be correlated with ambient temperature changes and temporal wavelength dependency.