Novel technique for accurate measurement of OSNR using a channel performance monitor (CPM)

Limitations of tunable-filter-based optical performance monitors (OPM) when used to measure optical signal-to-noise ratios (OSNR) are discussed theoretically and experimentally. An inexpensive technique for improving their OSNR measurement capability in both accuracy and range is described and verified experimentally for a dense wavelength-division multiplexed (DWDM) system.