Simultaneous Distributed Vibration and Temperature Sensing Using Multicore Fiber

Yunli Dang,Zhiyong Zhao,Chao Lu,Xuefeng Wang,Ruolin Liao

doi:10.1109/access.2019.2948213

Abstract

Distributed optical fiber sensing that enables simultaneous vibration and temperature monitoring is demonstrated in this work, which is achieved by implementing polarization optical time-domain reflectometry (P-OTDR) and Raman optical time-domain reflectometry (ROTDR) respectively through space-division multiplexed (SDM) configuration in different cores of a multicore fiber (MCF). Optimized system setup is obtained in the proposed hybrid system, where only one laser source is used, and the generated pulse is shared by the two reflectometers. Owing to the reason that separate interrogation fiber cores are used by the two reflectometers, the proposed hybrid system allows for simultaneous measurements of spontaneous Raman and Rayleigh scattering signals, thus it no longer suffers from the incompatible pump power levels issue, which results from different pump power demands, and hinders the implementation of the hybrid system in single mode fiber due to the fiber nonlinear effects imposed restriction. In addition, in order to extend the sensing range, we also explore the employment of wavelet transform denoising technique in the improvement of signal-to-noise ratio of ROTDR measurement. Eventually, simultaneous distributed vibration and temperature sensing in 5.76 km sensing range with 3 m spatial resolution and 0.57 °C temperature uncertainty has been demonstrated. The proposed hybrid sensing system has the outstanding advantage of high reliability, since the cross-sensitivity issue is effectively mitigated, which shows great potential for pipeline monitoring in oil and gas industry.

Highlights

The intelligent monitoring of environmental variation in the fields of civil, mining, and energy exploration has attracted ever increasing attention recently, where the environmental parameters are utilized to perceive the structure integrity and health condition, so that the safety and reliability of industrial operations can be enhanced notably
It is difficult to implement the hybrid polarization optical time-domain reflectometry (P-OTDR) and Raman optical time-domain reflectometry (ROTDR) sensing system simultaneously in a single mode fiber (SMF), because the spontaneous Raman scattering signal (SpRS) in optical fiber is very week, normally very high pump power is required for ROTDR and avalanche photodiode is needed for the detection of SpRS
We propose and experimentally demonstrate a multicore fiber (MCF) spatially multiplexed P-OTDR and ROTDR hybrid sensing system, where P-OTDR is used for vibration detection and ROTDR is employed for temperature monitoring

Summary

Introduction

The intelligent monitoring of environmental variation in the fields of civil, mining, and energy exploration has attracted ever increasing attention recently, where the environmental parameters (e.g. vibration, temperature and strain, etc.) are utilized to perceive the structure integrity and health condition, so that the safety and reliability of industrial operations can be enhanced notably. It is difficult to implement the hybrid P-OTDR and ROTDR sensing system simultaneously in a single mode fiber (SMF), because the spontaneous Raman scattering signal (SpRS) in optical fiber is very week, normally very high pump power is required for ROTDR (typically a few Watts) and avalanche photodiode is needed for the detection of SpRS.

Results

Conclusion