Measurements of PMD in the installed fiber plant of Deutsche Telekom

In this paper, PMD measurements that were carried out in the installed fiber plant of Deutsche Telekom, which consists solely of G.652 fiber, are presented. The measurements are performed all over Germany during the last three years on nearly 10,000 fiber sections whereby these fiber cables were installed from 1985 to 2001. It should be noted that pre-1994 cables PMD was not yet specified by cable manufacturers and PMD specification were only added around 1995. Fibers with lowest PMD were identified and reserved for high capacity transmission. The data indicate that no direct correlation of the first-order PMD coefficient value with the rollout of the PMD specification by the fiber and cable manufacturers is feasible. Even for cables which were installed during 1985 till 1991 a reasonable number of fibers is suitable for 40 Gbit/s transmission. For 10 Gbit/s selected fibers are used, thus PMD does not impose any limitations and therefore avoiding expensive exchange of fibers.