Development of a Phase-OTDR Interrogator Based on Coherent Detection Scheme

We present in this work, the experimental demonstration of a phase-sensitive Optical Time-Domain Reflectometer (phase-OTDR) having coherent detection scheme. An analysis algorithm has also been developed to calculate amplitude and phase evolution of the experimental phase-OTDR traces. The efficiency of the analysis algorithm to determine the position of the applied vibration has been verified for a single and two simultaneous vibrations. The slow-time analysis results show a good agreement with the mathematical calculations discussed in the paper. This work could have a technological iplication in many fields such as distributed vibration sensor for railway monitoring applications.