Distributed Brillouin Sensing: Time-Domain Techniques

Soto, Marcelo A.

doi:10.1007/978-981-10-1477-2_7-1

Cited by 18 publications

(34 citation statements)

References 57 publications

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“…Results in Figure 6 point out that the BFS estimations obtained by polynomial fitting match very well the values obtained by nonlinear double-Gaussian fitting, especially under large applied strains (i.e., large masses), when the two BGS peaks do not highly overlap. The obtained BFS values indeed also match the expected Brillouin spectral shifts based on the applied strain and the Brillouin strain coefficient of ~0.05 MHz/με [ 1 , 2 ]. In this large strain range, the evaluated root-mean-square BFS difference is 0.18 MHz and 1.1 MHz for the first and second peaks, respectively.…”

Section: Resultssupporting

confidence: 70%

“…This setup employs a 10 mW distributed feedback (DFB) laser operating at 1550 nm, whose light is split into two branches. In the upper branch (10%), an electro-optic modulator (EOM) with high extinction ratio is used to generate 20 ns optical pulses (providing 2 m spatial resolution) with about 40 dB extinction ratio, which is required to eliminate any continuous-wave Brillouin response along the sensing fiber [ 2 ]. Optical pulses are then boosted by an erbium-doped fiber amplifier (EDFA) and launched into the sensing fiber through an optical circulator with an optical power of ~100 mW (limit imposed by the onset of nonlinear effects such as modulation instability [ 14 ]).…”

Section: Methodsmentioning

confidence: 99%

“…For about three decades, Brillouin scattering has been widely used in the development of distributed optical fiber sensors. Exploiting the Brillouin acousto-optic interaction between optical signals and the optical fiber material, a distributed temperature or strain profile along an optical fiber can be obtained for sensing purposes [ 1 , 2 ]. The environmental information is contained on the peak frequency of the Brillouin gain spectrum (BGS), so-called Brillouin frequency shift (BFS) of the sensing fiber.…”

Section: Introductionmentioning

confidence: 99%

“…The environmental information is contained on the peak frequency of the Brillouin gain spectrum (BGS), so-called Brillouin frequency shift (BFS) of the sensing fiber. In the time-domain approach, the BGS is measured using optical pulses, whose length determines the spatial resolution of the sensor [ 2 ]. To extract the local temperature or strain information over the sensing optical fiber, measurements are post-processed to find the frequency of the BGS maximum amplitude at each fiber location [ 3 , 4 , 5 , 6 , 7 ].…”

Section: Introductionmentioning

confidence: 99%

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High-Order Polynomial Fitting Assistance for Fast Double-Peak Finding in Brillouin-Distributed Sensing

Soto

Jderu

Dorobantu

et al. 2020

Sensors

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A high-order polynomial fitting method is proposed to accelerate the computation of double-Gaussian fitting in the retrieval of the Brillouin frequency shifts (BFS) in optical fibers showing two local Brillouin peaks. The method is experimentally validated in a distributed Brillouin sensor under different signal-to noise ratios and realistic spectral scenarios. Results verify that a sixth-order polynomial fitting can provide a reliable initial estimation of the dual local BFS values, which can be subsequently used as initial parameters of a nonlinear double-Gaussian fitting. The method demonstrates a 4.9-fold reduction in the number of iterations required by double-Gaussian fitting and a 3.4-fold improvement in processing time.

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Section: Resultssupporting

confidence: 70%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

High-Order Polynomial Fitting Assistance for Fast Double-Peak Finding in Brillouin-Distributed Sensing

Soto

Jderu

Dorobantu

et al. 2020

Sensors

Self Cite

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“…DOFS emerged with the development of a technique called optical time-domain reflectometer (OTDR). There are three main types of OTDR sensing mechanism, which are based on Brillouin [20][21][22][23][24], Rayleigh [25][26][27][28][29], and Raman scattering [30,31].…”

Section: Introductionmentioning

confidence: 99%

The Field Monitoring Experiment of the Roof Strata Movement in Coal Mining Based on DFOS

Hou

2020

Sensors

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Mining deformation of roof strata is the main cause of methane explosion, water inrush, and roof collapse accidents amid underground coal mining. To ensure the safety of coal mining, the distributed optical fiber sensor (DFOS) technology has been applied in the 150,313 working face by Yinying Coal Mine in Shanxi Province, north China to monitor the roof strata movement, so as to grasp the movement law of roof strata and make it serve for production. The optical fibers are laid out in the holes drilled through the overlying strata on the roadway roof and BOTDR technique is utilized to carry out the on-site monitoring. Prior to the on-site test, the coupling test of the fiber strain in the concrete anchorage, the calibration test of the fiber strain coefficient of the 5-mm steel strand (SS) fiber, and the test of the strain transfer performance of the SS fiber were carried out in the laboratory. The approaches for fiber laying-out in the holes and fiber's spatial positioning underground the coal mine have been optimized in the field. The indoor test results show that the high-strength SS optical fiber has a high strain transfer performance, which can be coupled with the concrete anchor with uniform deformation. This demonstrated the feasibility of SS fiber for monitoring strata movement theoretically and experimentally; and the law of roof strata fracturing and collapse is obtained from the field test results. This paper is a trial to study the whole process of dynamic movement of the deformation of roof strata. Eventually the study results will help Yinying Coal Mine to optimize mining design, prevent coal mine accidents, and provide detailed test basis for DFOS monitoring technique of roof strata movement.both ends along the long axis direction; when the two cracks increase to a certain length, cracks appear in the middle of the short axis and propagate to both ends; second, the cracks continue to expand in the long axis and the short axis directions, and are penetrated by the arc curve at four corners to form an "O-shaped" closed crack curve; finally, the "X-shaped" cracks are full of the "O-shaped" closed curve. At this time, the four sides of the fixed support plate will break into four geometrically movable rock blocks, the four rock blocks will rotate sink to the goaf like a cantilever beam. With the collapse of the broken roof strata, the broken rock blocks accumulate to be a loose rock body, the loose body then support the sinking roof strata, finally the Voussoir Beam Structure forms, which the Key Block is simplified into an arch with three articulations [1][2][3]. At present, Voussoir Beam hypothesis is widely used in China to design and guide coal mining. According to the hypothesis, the overlying strata movement of stope is divided into three zones in horizontal and vertical direction, as shown in Figure 1. The overburden of stope is divided into caving zone, fracture zone, and bending subsidence zone from bottom to top. In the advancing direction of the working face, Block A represents the Key Block ...

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Enhancing fibre-optic distributed acoustic sensing capabilities with blind near-field array signal processing

Muñoz

Soto

2022

Nat Commun

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Distributed acoustic sensors (DAS) can monitor mechanical vibrations along thousands independent locations using an optical fibre. The measured acoustic waveform highly varies along the sensing fibre due to the intrinsic uneven DAS longitudinal response and distortions originated during mechanical wave propagation. Here, we propose a fully blind method based on near-field acoustic array processing that considers the nonuniform response of DAS channels and can be used with any optical fibre positioning geometry having angular diversity. With no source and fibre location information, the method can reduce signal distortions and provide relevant signal-to-noise ratio enhancement through sparse beamforming spatial filtering. The method also allows the localisation of the two-dimensional spatial coordinates of acoustic sources, requiring no specific fibre installation design. The method offers distributed analysis capabilities of the entire acoustic field outside the sensing fibre, enabling DAS systems to characterise vibration sources placed in areas far from the optical fibre.

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Distributed Brillouin Sensing: Time-Domain Techniques

Cited by 18 publications

References 57 publications

High-Order Polynomial Fitting Assistance for Fast Double-Peak Finding in Brillouin-Distributed Sensing

High-Order Polynomial Fitting Assistance for Fast Double-Peak Finding in Brillouin-Distributed Sensing

The Field Monitoring Experiment of the Roof Strata Movement in Coal Mining Based on DFOS

Enhancing fibre-optic distributed acoustic sensing capabilities with blind near-field array signal processing

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