A practical passive surveillance scheme for optically amplified passive branched optical networks

We propose and experimentally demonstrate a novel and practical surveillance scheme for in-service fault identification in passive optically amplified branched networks. This scheme does not require any wavelength-tunable light source as used in multiwavelength optical time-domain reflectometer (OTDR). Fiber-Bragg gratings are placed at some strategic positions on different fiber branches to slice and reflect the optical amplifier´s residual amplified spontaneous emission (ASE) power at some wavelengths other than the signal wavelengths. The conditions of the fiber link and optical amplifier at each branch can be monitored by constantly checking the reflected power level of the corresponding wavelength without suspending the in-service channels.