OPTICAL TRANSMISSION SYSTEM WITH RAMAN AMPLIFIERS COMPRISING A SUPERVISORY SYSTEM

摘要

An optical transmission system comprising a supervisory system of devices disposed along an optical link is disclosed. Counter-propagating Raman amplifiers are disposed along the optical link. Low-frequency supervisory signals are superimposed on the optical signals traveling on the optical link by suitable modulators in the devices disposed along the line. Counter-propagating Raman amplifiers amplify optical signals and do not introduce a substantial amount of attenuation on the low-frequency supervisory signals.