Long-term monitoring of polarization-mode dispersion of aerial optical cables with respect to line availability

Physical and technical limits become important when trying to increase data transfer rates to tens of gigabits and higher for already installed optical cables. Polarization-mode dispersion (PMD) is one of the crucial transmission constraints, especially for aerial cables exposed to environmental stresses. Optical fibers in the laboratory and three aerial optical fiber cable links across the Swiss alps were characterized with respect to PMD. Long-term measurement results are correlated to weather data along the cables, and predictions regarding line availability are made.