Measured Temporal Statistics of the DGD RMS-Value in Buried Optical Fibers

The behavior of the differential group delay (DGD) root-mean-square (rms) value is investigated for a buried G.652 fiber line in a metropolitan fiber plant outside Stockholm, Sweden. This study presents measurement results from two different measurement periods where the same fiber and the same measurement equipment was used. In total, ~ 2800 hours of measurements were performed. As expected, the recorded DGD rms-value varied with time. The measured standard deviation for the statistics of the DGD rms-value fits reasonably well with values presented in literature. The fiber line, which showed a DGD rms-value of 0.45 ps in average, had an extremely long time constant. Even after ~ 2800 hours of measurements we have not closed in on the expected asymptotic distribution of the measured DGD rms-value.