Patent ID: 7041959

Claim:
A system for monitoring the performance of DWDM multi-wavelength systems comprising: means for converting an optical signal for a particular wavelength from the DWDM multi-wavelength system to an electrical signal; means for processing the electrical signal to determine the performance of the DWDM multi-wavelength system at the particular wavelength and for controlling the converting means so that each particular wavelength of the DWDM multi-wavelength system is processed and wherein the converting means comprises: means for mixing the optical signal with a tunable reference optical signal to produce a combined optical signal; and a photodetector for converting the combined signal to the electrical, wherein the mixing means comprises: means for dividing the optical signal and the reference optical signal each into corresponding orthogonal polarized beams; and means for combining the respective polarized beams of like polarization to form a pair of combined optical signals as the combined optical signal.