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Journal ArticleDOI

Differential pulse-width pair BOTDA for high spatial resolution sensing

22 Dec 2008-Optics Express (Optical Society of America)-Vol. 16, Iss: 26, pp 21616-21625
TL;DR: A differential pulse-width pair Brillouin optical time domain analysis (DPP-BOTDA) for centimeter spatial resolution sensing using meter equivalent pulses is proposed.
Abstract: A differential pulse-width pair Brillouin optical time domain analysis (DPP-BOTDA) for centimeter spatial resolution sensing using meter equivalent pulses is proposed. This scheme uses the time domain waveform subtraction at the same scanned Brillouin frequency obtained from pulse lights with different pulse-widths (e.g. 50ns and 49ns) to form the differential Brillouin gain spectrum (BGS) at each fiber location. The spatial resolution is defined by the average of the rise and fall time equivalent fiber length for a small stress section rather than the pulse-width difference equivalent length. The spatial resolution of 0.18m for the 50/49ns pulse pair and 0.15m for 20/19ns pulse pair over 1km sensing length with Brillouin frequency shift accuracy of 2.6MHz are demonstrated.
Citations
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Journal ArticleDOI
26 Jun 2012-Sensors
TL;DR: A sensor with centimeter spatial resolution and high precision measurement of temperature, strain, vibration and birefringence can find applications in aerospace smart structures, material processing, and the characterization of optical materials and devices.
Abstract: Rayleigh, Brillouin and Raman scatterings in fibers result from the interaction of photons with local material characteristic features like density, temperature and strain. For example an acoustic/mechanical wave generates a dynamic density variation; such a variation may be affected by local temperature, strain, vibration and birefringence. By detecting changes in the amplitude, frequency and phase of light scattered along a fiber, one can realize a distributed fiber sensor for measuring localized temperature, strain, vibration and birefringence over lengths ranging from meters to one hundred kilometers. Such a measurement can be made in the time domain or frequency domain to resolve location information. With coherent detection of the scattered light one can observe changes in birefringence and beat length for fibers and devices. The progress on state of the art technology for sensing performance, in terms of spatial resolution and limitations on sensing length is reviewed. These distributed sensors can be used for disaster prevention in the civil structural monitoring of pipelines, bridges, dams and railroads. A sensor with centimeter spatial resolution and high precision measurement of temperature, strain, vibration and birefringence can find applications in aerospace smart structures, material processing, and the characterization of optical materials and devices.

1,011 citations


Cites methods from "Differential pulse-width pair BOTDA..."

  • ...Thanks to the innovative approaches of pre-pumping [90,95], differential Brillouin gain [91], and Brillouin echoes [97], distributed Brillouin sensors have achieved comparable spatial resolution to that of OFDR: 2 cm over 2 km and 2 °C temperature resolution [32] while the Rayleigh or stimulated Brillouin scattering based OFDR sensors have limited sensing length of less than 100 m [6,89]....

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  • ...To solve this problem, differential Brillouin gain detection using two pulses with slight pulse width difference was proposed [91], so that the spatial resolution can be determined as the pulse width difference instead of the pulse itself....

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Journal ArticleDOI
07 Apr 2011-Sensors
TL;DR: The progress on improving sensing performance parameters like spatial resolution, sensing length limitation and simultaneous temperature and strain measurement is reviewed.
Abstract: Brillouin scattering in optical fiber describes the interaction of an electro-magnetic field (photon) with a characteristic density variation of the fiber. When the electric field amplitude of an optical beam (so-called pump wave), and another wave is introduced at the downshifted Brillouin frequency (namely Stokes wave), the beating between the pump and Stokes waves creates a modified density change via the electrostriction effect, resulting in so-called the stimulated Brillouin scattering. The density variation is associated with a mechanical acoustic wave; and it may be affected by local temperature, strain, and vibration which induce changes in the fiber effective refractive index and sound velocity. Through the measurement of the static or dynamic changes in Brillouin frequency along the fiber one can realize a distributed fiber sensor for local temperature, strain and vibration over tens or hundreds of kilometers. This paper reviews the progress on improving sensing performance parameters like spatial resolution, sensing length limitation and simultaneous temperature and strain measurement. These kinds of sensors can be used in civil structural monitoring of pipelines, bridges, dams, and railroads for disaster prevention. Analogous to the static Bragg grating, one can write a moving Brillouin grating in fibers, with the lifetime of the acoustic wave. The length of the Brillouin grating can be controlled by the writing pulses at any position in fibers. Such gratings can be used to measure changes in birefringence, which is an important parameter in fiber communications. Applications for this kind of sensor can be found in aerospace, material processing and fine structures.

491 citations

Journal ArticleDOI
30 Jul 2015-Sensors
TL;DR: Recent research and applications in structural health monitoring of composite aircraft structures using FOS have been critically reviewed, considering both the multi-point and distributed sensing techniques.
Abstract: In-service structural health monitoring of composite aircraft structures plays a key role in the assessment of their performance and integrity. In recent years, Fibre Optic Sensors (FOS) have proved to be a potentially excellent technique for real-time in-situ monitoring of these structures due to their numerous advantages, such as immunity to electromagnetic interference, small size, light weight, durability, and high bandwidth, which allows a great number of sensors to operate in the same system, and the possibility to be integrated within the material. However, more effort is still needed to bring the technology to a fully mature readiness level. In this paper, recent research and applications in structural health monitoring of composite aircraft structures using FOS have been critically reviewed, considering both the multi-point and distributed sensing techniques.

461 citations


Cites methods from "Differential pulse-width pair BOTDA..."

  • ...Later, innovative approaches such as the use of pre-pumping [72], differential Brillouin gain [73] and Brillouin echoes [74], have lowered the spatial resolution down to 2 cm over 2 km, with accuracy of 20 με....

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Journal ArticleDOI
TL;DR: This work is focused on a review of three types of distributed optical fiber sensors which are based on Rayleigh, Brillouin, and Raman scattering, and use various demodulation schemes, including optical time-domain reflectometry, optical frequency-domainreflectometry, and related schemes.
Abstract: Over the past few decades, optical fibers have been widely deployed to implement various applications in high-speed long-distance telecommunication, optical imaging, ultrafast lasers, and optical sensors. Distributed optical fiber sensors characterized by spatially resolved measurements along a single continuous strand of optical fiber have undergone significant improvements in underlying technologies and application scenarios, representing the highest state of the art in optical sensing. This work is focused on a review of three types of distributed optical fiber sensors which are based on Rayleigh, Brillouin, and Raman scattering, and use various demodulation schemes, including optical time-domain reflectometry, optical frequency-domain reflectometry, and related schemes. Recent developments of various distributed optical fiber sensors to provide simultaneous measurements of multiple parameters are analyzed based on their sensing performance, revealing an inherent trade-off between performance parameters such as sensing range, spatial resolution, and sensing resolution. This review highlights the latest progress in distributed optical fiber sensors with an emphasis on energy applications such as energy infrastructure monitoring, power generation system monitoring, oil and gas pipeline monitoring, and geothermal process monitoring. This review aims to clarify challenges and limitations of distributed optical fiber sensors with the goal of providing a pathway to push the limits in distributed optical fiber sensing for practical applications.

329 citations

Journal ArticleDOI
TL;DR: A figure-of-merit is proposed to fairly compare the performance of Brillouin distributed sensing systems and offers the research community and potential users the possibility to evaluate with an objective metric the real performance gain resulting from any proposed configuration.
Abstract: A thorough analysis of the key factors impacting on the performance of Brillouin distributed optical fiber sensors is presented. An analytical expression is derived to estimate the error on the determination of the Brillouin peak gain frequency, based for the first time on real experimental conditions. This expression is experimentally validated, and describes how this frequency uncertainty depends on measurement parameters, such as Brillouin gain linewidth, frequency scanning step and signal-to-noise ratio. Based on the model leading to this expression and considering the limitations imposed by nonlinear effects and pump depletion, a figure-of-merit is proposed to fairly compare the performance of Brillouin distributed sensing systems. This figure-of-merit offers to the research community and to potential users the possibility to evaluate with an objective metric the real performance gain resulting from any proposed configuration.

318 citations

References
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Journal ArticleDOI
TL;DR: In this article, a distributed strain and temperature sensing technique that uses Brillouin scattering in single-mode optical fibers is presented, which is based on strain- and temperature-induced changes in the frequency shift.
Abstract: This paper reviews the developments of a distributed strain and temperature sensing technique that uses Brillouin scattering in single-mode optical fibers. This technique is based on strain- and temperature-induced changes in the Brillouin frequency shift. Several approaches for measuring the weak Brillouin line are compared. >

685 citations

Journal ArticleDOI
TL;DR: The feasibility of the highly precise simultaneous measurement of temperature and strain by use of the PCF in a distributed Brillouin sensing system with a spatial resolution of 15 cm is demonstrated.
Abstract: The dependence of the Brillouin frequency shift on strain in a photonic crystal fiber (PCF) was measured at a wavelength of 1320 nm for the first time to the authors’ knowledge. Together with measurements of the dependence of the Brillouin frequency shift on temperature in the PCF, we demonstrate the feasibility of the highly precise simultaneous measurement of temperature and strain by use of the PCF in a distributed Brillouin sensing system with a spatial resolution of 15 cm.

138 citations

Journal ArticleDOI
TL;DR: This study reveals the processes responsible for a broadening of the Brillouin loss curve when the probe pulse duration is reduced, followed by a sudden and rather surprising reduction of the linewidth when the pulse duration gets shorter than the acoustic relaxation time.
Abstract: We perform numerical simulations on a model describing a Brillouin-based temperature and strain sensor, testing its response when it is probed with relatively short pulses. Experimental results were recently published [e.g., Opt. Lett. 24, 510 (1999)] that showed a broadening of the Brillouin loss curve when the probe pulse duration is reduced, followed by a sudden and rather surprising reduction of the linewidth when the pulse duration gets shorter than the acoustic relaxation time. Our study reveals the processes responsible for this behavior. We give a clear physical insight into the problem, allowing us to define the best experimental conditions required for one to take the advantage of this effect.

101 citations

Journal ArticleDOI
TL;DR: The study reveals that the coherent portion inside the pulse length of these two interactions caused by the same phase is responsible for this behavior, and allows us to detect 1.5-cm outer-layer cracks on an optical ground-wire cable.
Abstract: We provide a theoretical explanation for a coherent probe-pump-based Brillouin sensor system that achieves centimeter spatial resolution with high-frequency resolution. It was recently discovered that, when a combination of cw and pulsed light (the probe beam) interacts with a cw laser (the pump beam), centimeter spatial resolution with high-frequency resolution can be achieved even though the probe-pulse duration is 1.5 ns [Opt. Lett.29, 1485 (2004)]. Our study reveals that the coherent portion inside the pulse length of these two interactions caused by the same phase is responsible for this behavior. It allows us to detect 1.5-cm outer-layer cracks on an optical ground-wire cable.

85 citations

Journal ArticleDOI
TL;DR: The strain measurement of a 1.65-m reinforced concrete beam by use of a distributed fiber strain sensor with a 50-cm spatial resolution and 5-cm readout resolution is reported.
Abstract: The strain measurement of a 1.65-m reinforced concrete beam by use of a distributed fiber strain sensor with a 50-cm spatial resolution and 5-cm readout resolution is reported. The strain-measurement accuracy is ±15 µe (µm/m) according to the system calibration in the laboratory environment with non-uniform-distributed strain and ±5 µe with uniform strain distribution. The strain distribution has been measured for one-point and two-point loading patterns for optical fibers embedded in pultruded glass fiber reinforced polymer (GFRP) rods and those bonded to steel reinforcing bars. In the one-point loading case, the strain deviations are ±7 and ±15 µe for fibers embedded in the GFRP rods and fibers bonded to steel reinforcing bars, respectively, whereas the strain deviation is ±20 µe for the two-point loading case.

61 citations