Single-Ended > 100-km Distributed Vibration Sensor Based on OFDR Using Pearson Correlation Coefficient

Distributed optical fiber vibration sensor (DOFVS) is an ideal technology for integrated sensing and communication in an optical fiber (ISAC-OF), which can be widely applied to urban structure health monitoring, ocean seismic detection, and pipelines/cable/border safety monitoring. In this article, we present a single-ended > 100-km distributed vibration sensor based on optical frequency-domain reflectometry (OFDR) by detecting Rayleigh backsca- ttering change that is evaluated by the Pearson correlation coefficient (Pearson-CC). By using a simple internal modula- tion OFDR system without any amplifier, specialty optical fiber, and complex modulation techniques, vibration events can be located by detecting changepoints in step form in the Pearson-CC, and the amplitude of vibration events is proportional to the differential Pearson-CC. A pruned exact linear time (PELT) algorithm is performed in the Pearson-CC along fiber under test (FUT) to detect all changepoints. In experiments, we achieve distributed vibration sensing (DVS) with a range of 100.9 km, a sensing spatial resolution of 15.3 m, and a strain resolution of 868 p<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\varepsilon $ </tex-math></inline-formula>. The differential Pearson-CC and amplitude of the vibration event have a good linear relationship, whose <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</i>-square reaches 0.9993. We also successfully located two simultaneous vibration events over 100-km fiber.