Optical signal-to-noise monitor having increased coherence

摘要

Methods and apparatus for rapid, accurate OSNR measurements by directly measuring the spectrally-resolved State of Polarization (SOP) variation across each DWDM channel and using a polarization controller to deterministically extinguish the signal across narrow frequency subbands within each DWDM channel. In-band ASE noise is subsequently measured as a function of frequency across the channel bandwidth.