Patent ID: 7203428
Filing Date: 2007-04-10
Classification: H04B

Abstract:
1. A method of monitoring polarization mode dispersion (PMD) to determine a PMD of one or more channels within an optical link comprising the steps of: a) providing a multiple wavelength optical signal comprising the one or more channels of defined wavelength bands; b) combining a narrow line width optical signal from a local tunable source having a selected wavelength with the multiple wavelength optical signal; c) splitting the combined narrow line width optical signal and the multiple wavelength optical signal into first and second beams of orthogonal polarization states such that optical power of the narrow line width optical signal is substantially equally divided; d) detecting an amplitude and phase of the first beam at a predetermined beat frequency with a first heterodyne detector; e) detecting an amplitude and phase of the second beam at the predetermined beat frequency with a second heterodyne detector; f) comparing the detected amplitude and phase of the first and second heterodyne detectors to determine a state of polarization (SOP) for the selected wavelength; g) tuning the narrow line width optical signal to another selected wavelength within a channel wavelength band; h) repeating steps a--f for a plurality of other selected wavelengths; i) determining the PMD for the channel wavelength band from the SOBs of the plurality of selected wavelengths.