PMD monitoring in traffic-carrying optical systems and its statistical analysis.

Differential group delay (DGD) experienced by the optical signal in in-service terrestrial optical fiber systems has been monitored for the first time without the requirement of looping-back, in which the live traffic carried in the fiber was used as the probing signal. The relationship between the measured DGD using this technique and the actual fiber PMD parameter is formulated and verified by field experiments.