In-service passive surveillance system for optically-amplified branched networks

The authors experimentally demonstrate a passive surveillance system for in-service fault identification in optically-amplified branched networks. The proposed scheme only requires fibre Bragg gratings to be placed on different fibre branches and needs no extra laser source as required in conventional and multi-wavelength OTDR. The reflected monitoring channels are demultiplexed by an array-waveguide grating and detected by a power sensor array. The link status of all fibre branches can be monitored continuously and simultaneously through the Internet