Centralised Optical Monitoring of Tree-structured Passive Optical Networks using a Raman-assisted OTDR

Monitoring of tree-structured passive optical networks from a central office is difficult to achieve using a standard OTDR. Switchable reflective elements placed at the ONU can help to discriminate between the branches. In parallel, a Raman assisted OTDR is shown to increase the dynamic range of the reflectometry measurement, thus enabling to detect more faults in the network, and especially fibre breaks after the splitter.