Fault localization in WDM passive optical network by reusing downstream light sources

We propose and demonstrate a simple and cost-effective technique to detect and localize the fiber failures in wavelength-division-multiplexed (WDM) passive optical networks. By reusing the downstream lasers as WDM light sources for the optical time-domain reflectometry, the proposed technique can localize the failures in both feeder and drop fibers without using the expensive tunable laser.