Abstract
In the past two decades Brillouin-based sensors have emerged as a newly-developed optical fiber sensing technology for distributed temperature and strain measurements. Among these, the Brillouin optical time domain reflectometer (BOTDR) has attracted more and more research attention, because of its exclusive advantages, including single-end access, simple system architecture, easy implementation and widespread field applications. It is realized mainly by injecting optical pulses into the fiber and detecting the Brillouin frequency shift (BFS), which is linearly related to the change of ambient temperature and axial strain of the sensing fiber. In this paper, the authors provide a review of new progress on performance improvement and applications of BOTDR in the last decade. Firstly, the recent advances in improving the performance of BOTDRs are summarized, such as spatial resolution, signal-to-noise ratio and measurement accuracy, measurement speed, cross sensitivity and other properties. Moreover, novel-type optical fibers bring new characteristics to optic fiber sensors, hence we introduce the different Brillouin sensing features of special fibers, mainly covering the plastic optical fiber, photonic crystal fiber, few-mode fiber and other special fibers. Additionally, we present a brief overview of BOTDR application scenarios in many industrial fields and intelligent perception, including structural health monitoring of large-range infrastructure, geological disaster prewarning and other applications. To conclude, we discuss several challenges and prospects in the future development of BOTDRs.
Highlights
Since extremely-low-loss glass optical fiber was first manufactured in 1970s [1], it has been treated as the optimal information transmission carrier for high-speed and super-capacity data communication systems
A practical technique named the equidistance difference optimum method proposed by He et al in 2013, which was capable of eliminating the distortion of the strain information was proposed by He et al in 2013, which was capable of eliminating the distortion of the strain arising from the mismatched caused by the measured fiber length being shorter than the spatial resolution (SR) during information arising from the mismatched caused by the measured fiber length being shorter than the the temperature and strain measurement by Brillouin optical time domain reflectometer (BOTDR) [41]
As early as in 2007, the fast Fourier transform (FFT) technique was utilized in BOTDR for quasi-real-time temperature or strain measurement over a 12.5 km sensing fiber with 1024 averages taken in only 1 second, eliminating the time-consuming frequency scanning process [96]
Summary
Since extremely-low-loss glass optical fiber was first manufactured in 1970s [1], it has been treated as the optimal information transmission carrier for high-speed and super-capacity data communication systems. Are based on the Brillouin interaction between pump pulse and probe continuous light waves simultaneously counterpropagating in optical fibers These techniques inevitably suffer from the disadvantage that both ends of the sensing fiber have to be accessed, which limits their application in some engineering fields. In terms of enhancing the SNR and measurement accuracy, many improved schemes were proposed based on hardware optimization, such as seed laser performance, probe pulse features and optical link structures. The recent advances of BOTDRs in the last decade are reviewed We discuss several challenges and prospects in the future development of BOTDRs
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