Brillouin optical correlation domain analysis with more than 1 million effective sensing points based on differential measurement

Kim, Yong Hyun; Lee, Kwanil; Song, Kwang Yong

doi:10.1364/oe.23.033241

Cited by 66 publications

(30 citation statements)

References 14 publications

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“…The most promising technique at the moment is represented by Brillouin optical correlation domain analysis, which enables measurements over a range of 10 km and beyond, with resolution better than 1 cm (i.e., with more than 1 million sensing points) [96,97].…”

Section: Brillouin-based Distributed Sensingmentioning

confidence: 99%

A Review of Distributed Fibre Optic Sensors for Geo-Hydrological Applications

2017

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Featured Application: Distributed fibre optic sensors for geo-hydrological applications: a comprehensive review about methodology, weaknesses, and strengths.Abstract: Distributed optical fibre sensing, employing either Rayleigh, Raman, or Brillouin scattering, is the only physical-contact sensor technology capable of accurately estimating physical fields with spatial continuity along the fibre. This unique feature and the other features of standard optical fibre sensors (e.g., minimal invasiveness and lightweight, remote powering/interrogating capabilities) have for many years promoted the technology to be a promising candidate for geo-hydrological monitoring. Relentless research efforts are being undertaken to bring the technology to complete maturity through laboratory, physical models, and in-situ tests. The application of distributed optical fibre sensors to geo-hydrological monitoring is here reviewed and discussed, along with basic principles and main acquisition techniques. Among the many existing geo-hydrological processes, the emphasis is placed on those related to soil levees, slopes/landslide, and ground subsidence that constitute a significant percentage of current geohazards.

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Section: Brillouin-based Distributed Sensingmentioning

confidence: 99%

A Review of Distributed Fibre Optic Sensors for Geo-Hydrological Applications

2017

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“…In previous research, the sensing information, i.e., the Brillouin gain peak along the fiber is obtained by curve fitting the gain profile point by point from one end to the other [3,[5][6][7][9][10][11]14,15,[20][21][22][23][24][26][27][28][29][30], and that profile ideally follows a Lorentzian shape as described below [31]…”

Section: Spectra Subtraction Theorymentioning

confidence: 99%

“…practice, the Brillouin gain spectrum is normally obtained by Lorentzian curve fitting point by point and then the sensing information is retrieved from the central Brillouin frequency [20]. However, on the way to a higher solution, especially with 1 million points and beyond [21][22][23][24], to in-site real-time dynamic measurements [25][26][27], and to extra fine frequency resolution [28][29][30], the curve fitting process takes a very long time and it is neither target oriented nor effective, which makes those goals hard to achieve and some even unrealistic. Actually, not every single point along the fiber needs to be curve fitted, because a large range of the fiber's Brillouin frequency may only have jitters in a measurement, which is not necessary to be calculated, and only those points with frequency changes carries information and need be fitted and calculated.…”

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confidence: 99%

Fast information acquisition using spectra subtraction for Brillouin distributed fiber sensors

Guo

Cao

et al. 2019

Opt. Express

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The traditional methods of extracting sensing information of a Brillouin distributed sensor is by curve fitting the Brillouin gain profiles along the fiber, we propose two concise and time-saving methods to process signals from only the frequency shifted section(s) of the fiber by subtracting the original spectrum from the sensing Brillouin spectrum. Experimental results validate that our methods can provide up to over 9 times faster information acquisition for a 10 km sensing fiber with 800 m frequency shifted section comparing with the traditional way. The proposed methods could be potentially attractive in getting information for the Brillouin distributed sensors as well as the Raman and Rayleigh distributed sensors especially when the processing speed is concerned.

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“…To overcome this limitation and achieve submetric spatial resolution, different approaches have been proposed based on frequency, correlation [5][6][7][8][9], or time- [10][11][12] domain approaches. All of these techniques aim at increasing the number of resolved sensing points in the fiber.…”

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confidence: 99%

“…Frequency-and correlation-domain approaches allow very sharp spatial resolutions (in the order of millimeters or a few centimeters), however the measurement range is typically limited to a few kilometers. Using correlation-based schemes, a significant increase in the number of resolved points has been demonstrated along fibers of several kilometers-long [6][7][8][9]; however, the total measurement time still remains extremely long, e.g., a few hours for 1 million points [6]. A most recent improvement has ultimately led to a remarkable state-of-the-art record, doubling the number of resolved points up to 2.1 million, in spite of an eight-fold increase in the acquisition time [9].…”

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confidence: 99%

Resolving 1 million sensing points in an optimized differential time-domain Brillouin sensor

et al. 2017

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A differential pulse-width pair (DPP) Brillouin distributed fiber sensor is implemented to achieve centimetric spatial resolution over distances of several kilometers. The presented scheme uses a scanning method in which the spectral separation between the two probe sidebands is kept constant, while the optical frequency of the pump is swept to scan the Brillouin spectral response. Experimental results show that this method avoids detrimental temporal distortions of the pump pulses, which in a standard implementation prevent the DPP method from operating over mid-to-long distances. Such a novel scanning procedure allows the resolving, for the first time in pure time-domain Brillouin sensors, of 1,000,000 sensing points, i.e., 1 cm spatial resolution over 10 km in a conventional acquisition time. Brillouin-based distributed optical fiber sensors have become an established sensing technology due to their ability to measure strain/temperature changes along tens of kilometers of fiber, making them very suitable to monitor large civil infrastructures. In particular, in Brillouin optical time-domain analysis (BOTDA), the interaction of two counter-propagating signals, a pulsed pump, and a continuous-wave (CW) probe signal allows for measuring the temperature-and straindependent Brillouin gain/loss response of the sensing fiber with a spatial resolution given by the pump pulse width [1]. The probe wave is most commonly generated by making use of double-sideband (DSB) intensity modulation to mitigate the depletion of the pump pulse power, particularly in long-range schemes [2]. However, it has been recently proven that DSB schemes also bring massive spectral and temporal distortion on the pump pulse at high probe powers, inducing severe deformations in the Brillouin gain and loss spectra, and ultimately impairing the Brillouin frequency shift (BFS) determination [3]. Such a distortion results from asymmetric gain and loss, affecting the pump pulse in the conventional probe sideband frequency scanning, and scales directly with the probe wave power. To operate in a safe range, i.e., within a power range that secures negligible spectral distortions, the probe power in such a BOTDA scheme is limited to roughly −5 dBm per sideband [3], thus limiting the best attainable signalto-noise ratio (SNR) and measurand precision [4].On the other hand, the non-instantaneous (∼10 ns) response time of the acoustic wave generated at each fiber location imposes another limitation to the conventional BOTDA sensing technique: it impacts the spatial resolution, which cannot be reliably improved below 1 m, using an isolated interrogating pulse. To overcome this limitation and achieve submetric spatial resolution, different approaches have been proposed based on frequency, correlation [5][6][7][8][9], or time-[10-12] domain approaches. All of these techniques aim at increasing the number of resolved sensing points in the fiber. Frequency-and correlation-domain approaches allow very sharp spatial resolutions (in the order of millimeters or a few...

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Brillouin optical correlation domain analysis with more than 1 million effective sensing points based on differential measurement

Cited by 66 publications

References 14 publications

A Review of Distributed Fibre Optic Sensors for Geo-Hydrological Applications

A Review of Distributed Fibre Optic Sensors for Geo-Hydrological Applications

Fast information acquisition using spectra subtraction for Brillouin distributed fiber sensors

Resolving 1 million sensing points in an optimized differential time-domain Brillouin sensor

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