Patent ID: 8787755

Claim:
A device for monitoring a polarization mode dispersion (PMD) effect in an optical signal, comprising: an optical coupler to split an input optical signal into a first optical signal having a polarization of the input optical polarization in a first optical path and a second optical signal having the polarization of the input optical polarization in a second, separate optical path; a first optical filter in the first optical path to filter the first optical signal to have a first optical bandwidth that is less than an input optical bandwidth of the input optical signal and is different from a second optical bandwidth of the second optical signal; a first optical detector coupled to the first optical path to measure a degree of polarization of the first optical signal after being filtered by the first optical filter; a second optical detector in the second optical path to measure a degree of polarization of the second optical signal; and a processing unit in communication with the first and second optical detectors to receive outputs of the first and second optical detectors, the processing unit processing the measured degree of polarization of the first optical signal and the measured degree of polarization of the second optical signal to determine a depolarization factor of the input optical signal to reflect the PMD effect in the input optical signal and to determine an optical to signal noise ratio of the input optical signal.