A High-Performance Optical Time-Domain Brillouin Distributed Fiber Sensor

Díaz, Silvia; Mafang, Stella Foaleng; Lopez-Amo, M.; Thévenaz, Luc

doi:10.1109/jsen.2008.926963

Cited by 62 publications

(61 citation statements)

References 7 publications

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“…In that case, the FoM ranged 2 principally due to the low resolution (10 m) of the system. With the introduction of pre-amplification [43], the range, as expected, was increased ~ 20 km (~ 8 dB) and the resolution reduced until 2 meters. Obviously, the FoM is enhanced but the performance can still not be considered optimum for long-range applications.…”

Section: Discussionsupporting

confidence: 61%

Limits of BOTDA Range Extension Techniques

et al. 2016

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Abstract-Brillouin-based temperature and strain sensors have attracted great attention of both the academic and industrial sectors in the past few decades due to their ability to perform distributed measurements. Particularly, Brillouin Optical Time Domain Analysis (BOTDA) systems have been applied in many different scenarios, proving particularly useful in those requiring especially wide coverage ranging extremely long distances, such as in civil structure monitoring, energy transportation or environmental applications. The extension of the measuring range in these sensors has therefore become one of the main areas of research and development around BOTDA. To do so, it is necessary to increase the Signal to Noise Ratio (SNR) of the retrieved signal. So far, several techniques have been applied in order to achieve this goal, such as pre-amplification before detection, pulse coding or Raman amplification. Here, we analyze these techniques in terms of their performance limits and provide guidelines that can assist in finding out which is the best configuration to break current range limitations. Our analysis is based on physical arguments as well as current literature results.Index Terms-Brillouin scattering, distributed optic fiber sensing, distributed Raman scattering, optical fibers, optical pulse coding. I. INTRODUCTIONMONG the different available techniques to perform distributed measurements of strain and temperature, Brillouin Optical Time-Domain Analysis (BOTDA) [1,2] is presently recognized as one of the most consolidated. This fiber sensing technology is widely used in different application domains (civil engineering, pipelines, fire detection, etc.). BOTDA technology finds its root on the non-linear optical effect occurring in optical fibers and called Stimulated Brillouin Scattering (SBS) [3]. SBS is an acousto-optic process that manifests as a narrowband amplification of a probe beam when an intense coherent pump light beam is introduced through the opposite end of a single-mode fiber. The distributed feature is provided to the BOTDA by pulsing the pump wave and analyzing the retrieved probe wave as function of the time-of-flight of the pump pulse within the fiber, as depicted in Fig.1.Range and resolution are two of the most important features of these systems, which are normally limited to 20-30 km with 1-2 meter resolution in standard systems [4]. Attenuation, an intrinsic fiber feature, is the limiting factor in terms of range as it reduces the intensity of the signals within the fiber, therefore decreasing the Signal to Noise Ratio (SNR) as the monitored distance increases. Resolution, which is set by the spatial length of the employed pump pulses, is restricted by the associated issues when the pulse duration is reduced. First, a spectral broadening will manifest on the retrieved wave (leading to a higher uncertainty) and also a shorter interaction length will be obtained among the pump and probe wave, leading to a corresponding SNR decrease. Both factors lead to a non-proportional increase of ...

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Section: Discussionsupporting

confidence: 61%

Limits of BOTDA Range Extension Techniques

et al. 2016

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“…In recent years, distributed optical fiber sensors based on stimulated Brillouin scattering (SBS) have attracted a great interest owing to their unique ability to carry out high-performance strain and temperature measurements over long distances [1,2]. In the time-domain approach, the so-called Brillouin optical time-domain analysis (BOTDA) [1][2][3], a pulsed pump beam and a counterpropagating continuouswave (CW) probe beam, at different frequencies, interact through the intercession of an acoustic wave.…”

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confidence: 99%

Simplex-coded BOTDA fiber sensor with 1 m spatial resolution over a 50 km range

et al. 2010

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In this Letter, we propose the use of optical pulse coding techniques for long-range distributed sensors based on Brillouin optical time-domain analysis (BOTDA). Compared to conventional BOTDA sensors, optical coding provides a significant sensing-range enhancement, allowing for temperature and strain measurements with 1 m spatial resolution over 50 km of standard single-mode fiber, with an accuracy of 2.2°C/44 , respectively. © 2010 Optical Society of America OCIS codes: 060.2370, 060.4370, 280.4788, 290.5900. In recent years, distributed optical fiber sensors based on stimulated Brillouin scattering (SBS) have attracted a great interest owing to their unique ability to carry out high-performance strain and temperature measurements over long distances [1,2]. In the time-domain approach, the so-called Brillouin optical time-domain analysis (BOTDA) [1-3], a pulsed pump beam and a counterpropagating continuouswave (CW) probe beam, at different frequencies, interact through the intercession of an acoustic wave. Power transfer between both optical beams takes place at any position along the fiber when the frequency offset between them is within the local Brillouin gain spectrum (BGS). The frequency showing maximum gain is called Brillouin frequency shift (BFS) and depends linearly on strain and temperature, allowing us to perform distributed sensing [1]. The best performance reported so far for long-range BOTDA sensors results in 2 m/5 m spatial resolution over 40 km/51 km single-mode fiber [2,3], where pump depletion and modulation instability are the main factors limiting the sensing range [1,4]. In this Letter, we propose, for what we believe to be the first time, the use of optical pulse coding in a BOTDA sensor. We demonstrate that this technique effectively enhances the signal dynamic range, resulting in an extension of the sensing distance in BOTDA-based systems and providing the best performance reported so far, to our knowledge, temperature and strain sensing with 1 m spatial resolution over 50 km of standard single-mode fiber with an accuracy of 2.2°C/44 at the far end of the fiber.In BOTDA sensors, the BGS is reconstructed along the fiber by sweeping the frequency offset ͑⌬͒ between the two counterpropagating optical signals around the BFS. Thus, intensity variations of the probe signal ⌬I CW are measured at the near end of the fiber ͑z =0͒ as a function of time t and ⌬ and can be expressed as [1] ͑1͒where I CWL is the input probe intensity at the far end of the fiber ͑z = L͒, ␣ is the fiber loss, L is the fiber length, v g is the group velocity, ⌬z is the spatial resolution related to the pump pulse duration, and g B ͑ , ⌬͒ and I P ͑ , ⌬͒ are the BGS and the pump intensity at position z = .From Eq. (1) we clearly notice that the CWintensity contrast ͑⌬I CW ͒ mainly depends on the spatial resolution and the pump intensity. Thus, when short spatial resolution is required, the energy transferred to the probe is actually small, reducing ⌬I CW . This feature leads to measurements with low signalto-noise r...

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“…In order to measure the BGS along the fiber, the frequency difference between the pump and probe is swept around the BFS, i.e. around ∼10.9 GHz at 1550 nm in standard single-mode fibers at room temperature and zerostrain applied [5]. In BOTDA sensors, the spatial resolution is obtained by using a pulsed pump signal (launched at the fiber input, z = 0) and the local BFS is measured by sweeping the frequency offset within a range of some hundreds of MHz around the BFS.…”

Section: Theorymentioning

confidence: 99%

“…Taking into account this upper limitation on the maximum pump and probe powers, the SNR cannot be effectively enhanced when maintaining a given spatial resolution. The sensing range could be increased by using longer pump pulses, enhancing the SNR but negatively affecting the achievable spatial resolution [5,6]. Thus, these non-local effects, as well as modulation instability, result in the main limitations on the maximum sensing distance in longrange BOTDA sensors [5,6].…”

Section: Theorymentioning

confidence: 99%

“…The spatial resolution is given by the pump pulse duration, and is ultimately limited to 1 m, corresponding to 10 ns pulse duration, when using standard BOTDA techniques. When aiming at long-range measurements with meter-scale spatial resolution [5,6], the short SBS interaction results in a weak measured signal, offering poor accuracy when measuring the BGS. On the other hand, a strong probe signal can induce pump depletion [3] or modulation instability [7], reducing the interaction between the pump and probe signal due to gain saturation.…”

Section: Introductionmentioning

confidence: 99%

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Long-range Brillouin optical time-domain analysis sensor employing pulse coding techniques

Soto¹,

Bolognini²,

Pasquale³

et al. 2010

Meas. Sci. Technol.

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In this paper we describe and implement a long-range Brillouin optical time-domain analysis (BOTDA) sensor, for both temperature and strain measurements, using optical pulse coding techniques. A theoretical analysis of Simplex coding applied to BOTDA systems is presented and experimentally demonstrated for both Brillouin loss and Brillouin gain configurations. With the proposed technique, ∼7.1 dB and ∼10.3 dB of signal-to-noise ratio improvements are demonstrated in BOTDA measurements using 127-bit and 511-bit Simplex codes, respectively. This feature allows us to extend the dynamic range of the measurements, overcoming the limitations to the maximum usable optical power imposed by pump depletion and modulation instability; thus, the sensing range can be extended by several tens of kilometers while keeping meter-scale spatial resolution. Experimental results show the capabilities of optical pulse coding techniques to achieve 1 m spatial resolution over 50 km of standard single-mode fiber enabling temperature and strain resolutions equal to 2.2 • C and 44 με, respectively.

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A High-Performance Optical Time-Domain Brillouin Distributed Fiber Sensor

Cited by 62 publications

References 7 publications

Limits of BOTDA Range Extension Techniques

Limits of BOTDA Range Extension Techniques

Simplex-coded BOTDA fiber sensor with 1 m spatial resolution over a 50 km range

Long-range Brillouin optical time-domain analysis sensor employing pulse coding techniques

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