Effects of modulated pulse format on spontaneous Brillouin scattering spectrum and BOTDR sensing system

Hao, Yunqi; Ye, Qing; Pan, Zhengqing; Cai, Haiwen; Qu, Ronghui; Yang, Zhongmin

doi:10.1016/j.optlastec.2012.04.025

Cited by 16 publications

(10 citation statements)

References 14 publications

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“…The characteristics analyzed above are found to be in good agreement with our experimental results from a Brillouin optical time domain reflectometer (BOTDR). A narrow linewidth laser with frequency shifted by acousto-optic modulator (AOM) was used as the probe in the experiment; and a Brillouin fiber laser was used as the local oscillator for heterodyne detection, as described in [ 7 , 8 , 9 ]. A 30 km long sensing fiber (SMF-28) was used in the experiments.…”

Section: Experimental Results and Data Processingmentioning

confidence: 99%

Brillouin Frequency Shift of Fiber Distributed Sensors Extracted from Noisy Signals by Quadratic Fitting

Zheng

Fang

Wang

et al. 2018

Sensors

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It is a basic task in Brillouin distributed fiber sensors to extract the peak frequency of the scattering spectrum, since the peak frequency shift gives information on the fiber temperature and strain changes. Because of high-level noise, quadratic fitting is often used in the data processing. Formulas of the dependence of the minimum detectable Brillouin frequency shift (BFS) on the signal-to-noise ratio (SNR) and frequency step have been presented in publications, but in different expressions. A detailed deduction of new formulas of BFS variance and its average is given in this paper, showing especially their dependences on the data range used in fitting, including its length and its center respective to the real spectral peak. The theoretical analyses are experimentally verified. It is shown that the center of the data range has a direct impact on the accuracy of the extracted BFS. We propose and demonstrate an iterative fitting method to mitigate such effects and improve the accuracy of BFS measurement. The different expressions of BFS variances presented in previous papers are explained and discussed.

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Section: Experimental Results and Data Processingmentioning

confidence: 99%

Brillouin Frequency Shift of Fiber Distributed Sensors Extracted from Noisy Signals by Quadratic Fitting

Zheng

Fang

Wang

et al. 2018

Sensors

Self Cite

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“…The tested pulse shapes included the rectangle, triangle, trapezoid, Lorentzian, Gaussian and hyperbolic-secant, as shown in Figure 7a. The experimental results indicated that the SNR of Brillouin power spectrum for trapezoidal pulse and triangular pulse was increased by 3 dB and 4.8 dB relative to that for the rectangular pulse with the same pulse width of 200 ns [53], and the highest measurement accuracy and the longest sensing range were provided by the Lorentz pulse [54]. This result provides a helpful guide for researchers to choose appropriate probe pulse shapes.…”

Section: Performance Improvement Of Botdrsmentioning

confidence: 99%

Recent Advances in Brillouin Optical Time Domain Reflectometry

Bai

Wang

et al. 2019

Sensors

100

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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.

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“…The mean square deviation of the time and frequency distribution of a signal is defined in (12) and (13) [16]. Equation (14) describes the Heisenberg uncertainty principle [17]:…”

Section: Time-frequency ( -) Localizationmentioning

confidence: 99%

“…In 2000, the same group announced that different pulse shapes would have different bandwidth of the spectrum and have different frequency-measurement error according to simulations [12]. Hao et al in 2013 compared three pulse shapes including trapezoidal, triangular, and rectangular pulses and expressed that the Brillouin spectrum power of the triangular pulse shape was higher than the power of other pulse shapes [10,14]. They also compared other pulse shapes, including Lorentzian, Gaussian, super Gaussian, and triangular shape, and concluded that the Lorentzian shape generated the biggest peak power of Brillouin spectrum and has the measurement accuracy when the Brillouin spectrum peak is set to the same level [11].…”

Section: Introductionmentioning

confidence: 99%

Time and Frequency Localized Pulse Shape for Resolution Enhancement in STFT-BOTDR

Luo

et al. 2016

Journal of Sensors

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Short-Time Fourier Transform-Brillouin Optical Time-Domain Reflectometry (STFT-BOTDR) implements STFT over the full frequency spectrum to measure the distributed temperature and strain along the optic fiber, providing new research advances in dynamic distributed sensing. The spatial and frequency resolution of the dynamic sensing are limited by the Signal to Noise Ratio (SNR) and the Time-Frequency (T-F) localization of the input pulse shape.T-Flocalization is fundamentally important for the communication system, which suppresses interchannel interference (ICI) and intersymbol interference (ISI) to improve the transmission quality in multicarrier modulation (MCM). This paper demonstrates that theT-Flocalized input pulse shape can enhance the SNR and the spatial and frequency resolution in STFT-BOTDR. Simulation and experiments ofT-Flocalized different pulses shapes are conducted to compare the limitation of the system resolution. The result indicates that rectangular pulse should be selected to optimize the spatial resolution and Lorentzian pulse could be chosen to optimize the frequency resolution, while Gaussian shape pulse can be used in general applications for its balanced performance in both spatial and frequency resolution. Meanwhile,T-Flocalization is proved to be useful in the pulse shape selection for system resolution optimization.

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Effects of modulated pulse format on spontaneous Brillouin scattering spectrum and BOTDR sensing system

Cited by 16 publications

References 14 publications

Brillouin Frequency Shift of Fiber Distributed Sensors Extracted from Noisy Signals by Quadratic Fitting

Brillouin Frequency Shift of Fiber Distributed Sensors Extracted from Noisy Signals by Quadratic Fitting

Recent Advances in Brillouin Optical Time Domain Reflectometry

Time and Frequency Localized Pulse Shape for Resolution Enhancement in STFT-BOTDR

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