Highly sensitive reflectometry over 20 km with sub-meter spatialresolution based on phase-noise-compensated optical frequencydomain reflectometry and concatenative reference method

摘要

Highly sensitive reflectometry over 20 km with a sub-meter spatial resolution based on phase noise compensated optical frequency domain reflectometry and the concatenative reference method is proposed and demonstrated experimentally. A fiber laser is used as a light source to extend the measurement range although the distance remains limited to the laser coherence length because of the existence of laser phase noise. To reduce the influence of laser phase noise, the measurement signal is compensated using reference signals generated from a single auxiliary interferometer supported by a newly developed compensation process. By using the proposed technique, the measurement range is extended to 20 km with a sub-meter resolution and a sensitivity (relative to the Rayleigh backscattering level) of about -30 dB, which is nearly impossible to realize with the OTDR technique. The entire measurement time is 20 ms and the processing time is 20 s for each section.