A BOTDA with break interrogation function over 72 km sensing length

Hu, Junhui; Zhang, Xuping; Yao, Yuguo; Zhao, Xiaodong

doi:10.1364/oe.21.000145

Cited by 17 publications

(4 citation statements)

References 20 publications

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“…This method has the disadvantages of being susceptible to noise interference and complicated configuration system. Compared with the above methods, fiber grating sensors have the advantages of high sensitivity, lightweight, and antinoise interference, which are widely used in structural health monitoring [8,9]. At the same time, sensor networks can be constructed with space-division multiplexing and wavelength division multiplexing [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Reconstruction Technology of Flexible Structure Shape Based on FBG Sensor Array and Deep Learning Algorithm

Huang¹,

Jie²,

Zhang³

et al. 2022

Structural Durability &Amp; Health Monitoring

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A structural displacement field reconstruction method is proposed to aim at the problems of deformation monitoring and displacement field reconstruction of flexible plate-like structures in the aerospace field. This method combines the deep neural network model of the cross-layer connection structure with the fiber grating sensor network. This paper first introduces the principle of strain detection of fiber grating sensor, studies the mapping relationship between strain and displacement, and proposes a strain-displacement conversion model based on an improved neural network. Then the intelligent structure deformation monitoring system is built. By controlling the stepping distance of the motor to produce different deformations of the plate structure, the strain information and real displacement information are obtained based on the high-density fiber grating sensor network and the dial indicator array. Finally, based on the deformation prediction model obtained by training, the displacement field reconstruction of the structure under different deformation states is realized. Experimental results show that the mean absolute error of the deformation of the measuring points obtained by this method is less than 0.032 mm. This method is feasible in theory and practice and can be applied to the deformation monitoring of aerospace vehicle structures.

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Section: Introductionmentioning

confidence: 99%

Reconstruction Technology of Flexible Structure Shape Based on FBG Sensor Array and Deep Learning Algorithm

Huang¹,

Jie²,

Zhang³

et al. 2022

Structural Durability &Amp; Health Monitoring

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“…1 Brillouin optical time-domain analysis (BOTDA) sensors based on SBS interaction have gained much attention over the world since 1989, 2 owing to its superiority in distributed monitoring of temperature or strain in km-long fibers at a submeter resolution. [3][4][5][6][7] The measurement of temperature or strain in conventional BOTDA sensor is based on the linear relationship between the BFS and temperature or strain, and the BFS is usually measured by scanning the gain or loss spectrum of SBS amplitude and locating the peak value of the spectrum. Unfortunately, the measurement accuracy in the amplitude spectrum-based system is limited by pump depletion and nonlocal effect.…”

Section: Introductionmentioning

confidence: 99%

High-accuracy Brillouin frequency shift measurement system based on stimulated Brillouin scattering phase shift

et al. 2017

Opt. Eng

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, "High-accuracy Brillouin frequency shift measurement system based on stimulated Brillouin scattering phase shift," Opt. Eng. 56(5), 056102 (2017), doi: 10.1117/1.OE.56.5.056102. Abstract. A high-accuracy Brillouin frequency shift (BFS) measurement system for vector Brillouin optical timedomain analysis-based temperature sensor is proposed, in which double sideband modulation is used and the stimulated Brillouin scattering (SBS) gain and loss processes work together to generate a superimposed SBS phase-shift spectrum. The measurement principle is analyzed by mathematical modeling and the proof-of-concept experiment is performed by using a 100-m long standard single-mode fiber. The theoretical and experimental results reveal that the temperature sensitivity of BFS obtained from the measured SBS phase-shift spectrum is 1.059 MHz∕°C, and the measurement error of temperature is only half that in traditional single sideband-based system, which indicates that the proposed technique can realize high-accuracy temperature measurement and have huge potential in the field of long-distance and high-accuracy sensing. © The Authors. 1 Introduction Stimulated Brillouin scattering (SBS) in silica fiber is described as a nonlinear interaction between two counterpropagating optical waves with a frequency difference of Brillouin frequency shift (BFS) mediated through an acoustic wave, which not only transfers energy between these two optical waves but also changes their phases.1 Brillouin optical time-domain analysis (BOTDA) sensors based on SBS interaction have gained much attention over the world since 1989, 2 owing to its superiority in distributed monitoring of temperature or strain in km-long fibers at a submeter resolution.3-7 The measurement of temperature or strain in conventional BOTDA sensor is based on the linear relationship between the BFS and temperature or strain, and the BFS is usually measured by scanning the gain or loss spectrum of SBS amplitude and locating the peak value of the spectrum. Unfortunately, the measurement accuracy in the amplitude spectrum-based system is limited by pump depletion and nonlocal effect. [8][9][10][11] In recent years, however, the vector BOTDA (VBOTDA) system capable of measuring both the amplitude and phase-shift spectra of SBS response is introduced by Dossou et al.,12 and is used to feature the high-order acoustic resonances that are not clear on the SBS amplitude spectrum, by the SBS phase-shift spectrum. Since the temperature-or strain-induced BFS change results in a frequency shift of the SBS phase-shift spectrum, and the BFS can be measured by scanning the SBS phase-shift spectrum and locating its zero point, the SBS phase shift is also applied in BOTDA sensor to measure temperature or strain. A BOTDA sensor employing optical self-heterodyne detection and synchronous demodulation achieved a distributed phase-shift measurement over a 25-km long fiber and

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“…However, DSB modulation is very sensitive to chromatic dispersion (CD) of the sensing fiber, causing PM-IM conversion and power fading, and further introducing crosstalk in the measured BGS. [11][12][13][14] Recently, we have proposed a coherent BOTDA sensing scheme with single-sideband (SSB) modulation to reduce the effect of CD. 15 By taking advantage of this approach, CD can be suppressed significantly.…”

Section: Introductionmentioning

confidence: 99%

Enhanced performance for differential detection in coherent Brillouin optical time-domain analysis sensors

Shao

Zhang

et al. 2016

Opt. Eng

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Abstract. Logarithmic detectors (LogDs) have been used in coherent Brillouin optical time-domain analysis (BOTDA) sensors to reduce the effect of phase fluctuation, demodulation complexities, and measurement time. However, because of the inherent properties of LogDs, a DC component at the level of hundreds of millivolts that prohibits high-gain signal amplification (SA) could be generated, resulting in unacceptable data acquisition (DAQ) inaccuracies and decoding errors in the process of prototype integration. By generating a reference light at a level similar to the probe light, differential detection can be applied to remove the DC component automatically using a differential amplifier before the DAQ process. Therefore, high-gain SA can be employed to reduce quantization errors. The signal-to-noise ratio of the weak Brillouin gain signal is improved from ∼11.5 to ∼21.8 dB. A BOTDA prototype is implemented based on the proposed scheme. The experimental results show that the measurement accuracy of the Brillouin frequency shift (BFS) is improved from AE1.9 to AE0.8 MHz at the end of a 40-km sensing fiber. 1 Introduction Distributed optical fiber sensors based on Brillouin scattering have attracted widespread attention because of their characteristic abilities to achieve high-performance strain and temperature measurements over long distances.1-3 Among these Brillouin fiber sensor techniques, the Brillouin optical timedomain analysis (BOTDA) based on stimulated Brillouin scattering (SBS) exploits the dependence of the BFS parameter on strain and temperature, achieving highly accurate measurements over distances of more than several tens of kilometers. 4,5 Aiming for higher measurement accuracy, longer sensing distance, and higher spatial resolution, many efforts such as pulse coding, Raman amplification, and frequency comb have been devoted to improve the signal-to-noise ratio (SNR) and reduce measurement time of the BOTDA sensors. [6][7][8][9] Recently, coherent detection as a new method has been proposed, in which a local light beat and a probe light beam propagate through a photodetector (PD) by generating a GHz carrier to carry the Brillouin gain spectrum (BGS), resulting in significant SNR improvement (>10 dB typically) because of strong baseband noise perturbation reduction.

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A BOTDA with break interrogation function over 72 km sensing length

Cited by 17 publications

References 20 publications

Reconstruction Technology of Flexible Structure Shape Based on FBG Sensor Array and Deep Learning Algorithm

Reconstruction Technology of Flexible Structure Shape Based on FBG Sensor Array and Deep Learning Algorithm

High-accuracy Brillouin frequency shift measurement system based on stimulated Brillouin scattering phase shift

Enhanced performance for differential detection in coherent Brillouin optical time-domain analysis sensors

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