Abstract: At a receiver a 20 Gbit/s soliton bit stream is demultiplexed into two 10 Gbit/s bit streams using a 2-way splitter, a clock extraction circuit, and a pair of polarization insensitive amplitude modulators exhibiting positive chirp. The outputs of the modulators are fed to detectors via lengths of optical fiber exhibiting normal dispersion thereby producing bit streams with increased mark/space ratio and reduced timing jitter.

Abstract: An Optical Transmission System includes a monitor for outputting monitored data representative of the extent to which an optical signal is degraded by polarization mode dispersion. The monitor measures the degree of depolarization present in a sample of the optical signal derived from an optical tap, the depolarization being associated with polarization variation at the bit rate frequency of a signal data stream carried by the optical signal. The monitored data is used to control operation of the system to reroute the optical path taken by the optical signal in the event of a threshold level of polarization mode dispersion being exceeded. A transmitter of the optical signal may also be controlled to minimize polarization mode dispersion by varying the polarization state of the optical signal at launch so as to reduce the measured monitor data. The monitor functions during normal transmission of optical signals without the need for shutting down links of the system for measurement purposes.