OTDR reach extension for monitoring of high‐loss optical links

Centralized monitoring of high-loss optical fiber links is a major concern for network operators. Despite the recurrent deployment of optical time domain reflectometry (OTDR) techniques, which have been progressively improved over the past few decades, proposed solutions still lack the required dynamic range for achieving long distances and, at the same time, high resolution. This is especially true for long-reach passive optical networks, where large losses due to fiber attenuation and high split ratios of passive splitters are commonplace. In this article, we present a novel technique that uses a semiconductor optical amplifier in existing repeater nodes in such a way that incoming OTDR pulses are synchronously amplified, whereas backscattered light is kept unaffected. This method is capable of improving the OTDR dynamic range in a completely transparent way to OTDR settings such as operating wavelength, pulse duration, and repetition rate. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:974–977, 2014