Rating the performance of a Brillouin distributed fiber sensor

Thévenaz, Luc; Soto, Marcelo A.

doi:10.1117/12.975290

Cited by 8 publications

(9 citation statements)

References 18 publications

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“…The standard deviation of the obtained BFS between five consecutive traces at the very beginning of the fiber (first 5000 points window) is ∼0.618 MHz for both single sidebands acquisitions and ∼0.432 MHz for the balanced case. The standard deviation is improved by a factor of ∼ √ 2, in consistency with the SNR improvement expected in the balanced case (see [14] for details on the relationship between SNR and frequency estimation error). At the end of the fiber under test (last 5000 points window), the standard deviation for the single sideband cases is ∼1.232 MHz and, as expected, for the balanced detection case it is ∼0.884 MHz, also resulting in an improvement ratio of ∼ √ 2.…”

Section: Resultssupporting

confidence: 56%

“…At the end of the fiber under test (last 5000 points window), the standard deviation for the single sideband cases is ∼1.232 MHz and, as expected, for the balanced detection case it is ∼0.884 MHz, also resulting in an improvement ratio of ∼ √ 2. In terms of the figure-of-merit discussed by [14], the FOM calculated at the end of the fiber is 25.28 for the single sideband detection cases, and raises up to 35.24 for the balanced detection case, confirming the ∼ √ 2 improvement factor.…”

Section: Resultssupporting

confidence: 54%

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Signal-to-Noise Ratio Improvement in BOTDA Using Balanced Detection

Dominguez-Lopez

Lopez-Gil

Martín‐López

et al. 2014

IEEE Photon. Technol. Lett.

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Abstract-Brillouin optical time domain analysis (BOTDA) relies typically on the interaction among two counter-propagating waves: 1) a pulsed pump wave and 2) a modulated probe wave. The modulated probe wave has typically two sidebands, located at ±ν B with respect to the pump frequency. Conventional systems detect the time-resolved gain/loss by detecting only the upper/lower wavelength sideband. In this letter, we show that BOTDA can strongly benefit from the use of balanced detection among the two sidebands. In particular, the detected signal can be doubled while the noise only grows by a factor of (2) 1/2 , leading to a (2) 1/2 signal-to noise ratio (SNR) increase. Moreover, any common-mode noise in the probe signal path (e.g., master laser noise, modulator drifts, and so forth) is eliminated, rendering the system more robust. We validate the principle by experimental results that highlight the benefits of the technique in terms of the SNR.Index Terms-Brillouin scattering, distributed optic fiber sensor, balanced detection, temperature sensor.

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Section: Resultssupporting

confidence: 56%

Section: Resultssupporting

confidence: 54%

Signal-to-Noise Ratio Improvement in BOTDA Using Balanced Detection

Dominguez-Lopez

Lopez-Gil

Martín‐López

et al. 2014

IEEE Photon. Technol. Lett.

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“…This is a direct consequence of the offbaseband detection at RF frequency. The Brillouin frequency shift along the fibre has been estimated by fitting a quadratic curve over the BGS [8] and is represented in Fig. 4.…”

Section: Experimental Implementation and Resultsmentioning

confidence: 99%

Brillouin distributed fibre sensing using phase modulated probe

Soto

Gonzalez-Herraez

et al. 2013

SPIE Proceedings

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A novel configuration for a Brillouin distributed sensor using a phase modulated probe is presented. It offers the combined advantages of a direct implementation using simple devices and a large immunity to noise, shifting the information from the baseband to a higher frequency, which substantially strengthens the robustness to perturbations, interferences and other optical coherent noises. It naturally facilitates the possibility to perform frequency-coding on the probe to realise dynamic and fast measurements, since all frequency tunings are realised at sub-GHz frequencies.

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“…From that interaction, the power gained by the probe wave (from the pump wave), as represented in Fig.2, can be expressed as [6]:…”

Section: Conventional Botda Range Limitationsmentioning

confidence: 99%

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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Rating the performance of a Brillouin distributed fiber sensor

Cited by 8 publications

References 18 publications

Signal-to-Noise Ratio Improvement in BOTDA Using Balanced Detection

Signal-to-Noise Ratio Improvement in BOTDA Using Balanced Detection

Brillouin distributed fibre sensing using phase modulated probe

Limits of BOTDA Range Extension Techniques

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