Improving the accuracy of mean DGD estimates by analysis of second-order PMD statistics

The authors propose a novel technique to improve accuracy in measurements of the mean differential group delay (DGD) of optical fiber. Using the statistics of the second-order polarization-mode dispersion and averaging properly, they find a 30% reduction in measurement uncertainty, which is equivalent to doubling the measurement\´s optical bandwidth. The authors motivate the necessity for proper averaging by first demonstrating that the conventional conversions of "mean-square" to "mean" DGD lead to (correctable) systematic errors for finite bandwidth measurements.