Performance supervision for multiple optical amplifiers in WDM transmission systems using spectral analysis

In this letter, we propose and experimentally demonstrate a novel supervisory scheme to monitor the working status of multiple optical amplifiers in a wavelength-division-multiplexing transmission link. An optical feedback loop with unique loop length is added around each inline optical amplifier to create monitoring signal at a common supervisory wavelength. By analyzing the RF spectra of the common supervisory wavelength at the receiver end, any failed optical amplifier in the transmission link can be identified.