Fault localization of optical WDM submarine cable networks using coherent-optical time-domain reflectometry

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This letter describes fault localization in the optical wavelength-division-multiplexing (WDM) submarine cable networks by coherent-optical time domain reflectometry (C-OTDR). Using the bidirectional system designed for WDM signal transmission and a wavelength add/drop branching unit [add/drop branching unit (BU)] circuit, the trunk path, the branch path and the add/drop BU circuit were successfully surveyed by C-OTDR with wavelength tunability. It is very effective to conduct fault localization even in the optical WDM submarine cable networks by the same way as in the conventional single-channel systems.