Long-Range (>100km) Distributed Vibration Sensor based on Φ-OTDR Technique with Spread Amplification and Detection of Probe Pulses

This paper presents a set of results to demonstrate a long-range (>100km) distributed vibration sensor (DAS) based on the Coherent Optical Time Domain Reflectometry (Φ-OTDR) technique using distributed amplification of the probe pulses and detection of the backscattered traces, which demonstrates great capability to achieve long-range distances with great sensitivity. In this case, optical amplifiers have been placed along the sensing optical fiber, each one followed by a detection stage. Results for some traces detected in each of the spans along the sensing fiber, and some measurements of stimuli produced by a vibration at the end of each of the sections of the sensing fiber, are showed here. This work, framed in the project SACOH (Long-range Distributed Vibration Sensing by Coherent Rayleigh Backscattering), has been carried out in collaboration between the University of Zaragoza and the company APL (Aragon Photonics Labs).