TECHNIQUE FOR MONITORING OPTICAL PATHS

An optical repeater, having two optical amplifiers (OAs) for two optical paths, has optical pathways for providing, for each OA, looped-back incoming and amplified outgoing supervisory signals of the same wavelength but separated in time to enable independent characterization of the amplitudes of the incoming and amplified outgoing supervisory signals. When configured to operate with two different supervisory wavelengths, one for each OA, both OAs can be characterized simultaneously by two different landing stations, each transmitting a supervisory signal having a different supervisory wavelength.