Optical performance monitor with tunable filter and simultaneous gas cell wavelength reference

A new method of DWDM performance monitor with a tunable filter and a gas cell wavelength reference was demonstrated. With simultaneous scanning and sampling in different FRSs, wavelength, power, and signal-to-noise ratio in a DWDM system can be measured and computed simultaneously and accurately. The wavelength accuracy is also improved because gas cell references are insensitive to temperature variations. Because the spectrum of the wavelength reference is in a different FSR and is separable with the DWDM channels, reliability will be improved by eliminating the use of optical-mechanical switch.