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Jeff Smith

Bio: Jeff Smith is an academic researcher from University of New Brunswick. The author has contributed to research in topics: Brillouin scattering & Brillouin zone. The author has an hindex of 7, co-authored 8 publications receiving 324 citations.

Papers
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Journal ArticleDOI
TL;DR: It was found that the Brillouin-loss signal intensity is linearly related to the duration of the pump pulse used to obtain the spectrum, and three distinct behaviors were observed in the spectral linewidth.
Abstract: The characterization of the Brillouin-loss spectrum of single-mode fibers with very short (<10-ns) pulses has been studied. It was found that the Brillouin-loss signal intensity is linearly related to the duration of the pump pulse used to obtain the spectrum. In contrast with the uniform trend of the signal, three distinct behaviors were observed in the spectral linewidth. At long pulse durations the linewidth was constant at approximately 40 MHz. Pulse durations of the order of the phonon lifetime resulted in a broader spectrum, reaching a maximum width of ~100 MHz at 5 ns. Reducing the pulse duration further resulted in a sudden narrowing of the Brillouin line.

162 citations

Journal ArticleDOI
TL;DR: A new technique is reported that permits the simultaneous measurement of strain and temperature to resolutions of +/-178 microepsilon and +/-3.9 degrees C at a spatial resolution of 3.5 m by incorporation of the Brillouin-loss peak power with the conventional BrillouIn-frequency measurement.
Abstract: Brillouin-scattering-based sensors are capable of measuring either the strain or the temperature along the length of an optical fiber in a distributed fashion through measurement of the Brillouin-frequency shift. The cross sensitivity of the frequency shift to these two parameters makes it impossible to differentiate between them by measurement of the frequency shift alone. We report on a new technique that permits the simultaneous measurement of strain and temperature to resolutions of +/-178 microepsilon and +/-3.9 degrees C at a spatial resolution of 3.5 m by incorporation of the Brillouin-loss peak power with the conventional Brillouin-frequency measurement.

80 citations

Journal ArticleDOI
TL;DR: In this article, a distributed sensor for smart civil structures using Brillouin loss has been presented, which is capable of measuring strain or temperature at any region on a sensing fiber, even those that are kilometers in length.
Abstract: Over the past four years the Fibre Optics Group at the University of New Brunswick has been developing a distributed sensor for use in smart civil structures. By using Brillouin loss, the sensor is capable of measuring strain or temperature at any region on a sensing fibre, even those that are kilometers in length. This paper outlines the development of the sensor system, and discusses some of the experiments that have been performed with it. New results are presented that demonstrate 100 mm spatial resolution under laboratory conditions. This represents a four-fold improvement in the spatial resolution over previously reported results attained with a Brillouin scattering based distributed sensor.

33 citations

Journal ArticleDOI
TL;DR: In this article, the dependance of the Brillouin loss spectrum on the pump pulse width was studied. And the authors showed the nonlinear variations in the peak power and linewidth over a range of pulse widths from 10 to 4000 ns.

30 citations

Proceedings ArticleDOI
31 May 1999
TL;DR: In this paper, the Brillouin loss spectrum peak power was determined as a function of strain and temperature at a spatial resolution of 3.5 meters by combining this information with the conventional BrillouIN frequency measurement.
Abstract: Recent improvements to Brillouin scattering based distributed sensors have reduced both the spatial and strain resolutions to the point where they are acceptable for many smart structures applications. This type of optical fiber sensor can measure both strain and temperature as both parameters produce a change in the optical fiber's Brillouin frequency. Since both measurands have the same observed effect it is impossible to determine which measurand is responsible for the shift in frequency. This problem must be overcome for these sensors to be suitable for many smart structures applications. Techniques have recently been developed for Brillouin scattering based distributed sensor systems to separate strain and temperature information. However, these methods are limited theoretically to spatial resolutions approaching 5 - 10 meters. This paper reports on a new technique that was used at a shorter spatial resolution. The Brillouin loss spectrum peak power was determined as a function of strain and temperature at a spatial resolution of 3.5 meters. By combining this information with the conventional Brillouin frequency measurement, strain and temperature were successfully differentiated.

12 citations


Cited by
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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

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
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

Journal ArticleDOI
TL;DR: In this article, the state of the art of the leading Brillouin interrogation methods, with emphasis on the significant progress made in the last 3 years, are described, as well as a short introduction to coding, which has proven instrumental in many recently obtained performance records.
Abstract: Fiber-optic distributed sensing, employing the Brillouin effect, is already a commercially available measurement technique for the accurate estimation of the static strain/temperature fields along tens of kilometers with a spatial resolution of the order of a meter. Furthermore, relentless research efforts are paving the way to even much wider usability of the technique through recently achieved enhanced performance in each of its critical dimensions: measurement range has been extended to hundreds of kilometers; spatial resolution is of the order of a centimeter or less, signal to noise ratio has been significantly improved; fast dynamic events can be captured at kHz’s sampling rates; and a much better understanding of the underlying physics has been obtained, along with the formulation of figures of merit, and the preparation and early adoption of appropriate standards and guidelines. This paper describes the basics, as well as the state of the art, of the leading Brillouin interrogation methods, with emphasis on the significant progress made in the last 3 years. It also includes a short introduction to coding, which has proven instrumental in many of the recently obtained performance records.

261 citations

BookDOI
01 Jan 2001
TL;DR: Smart technology for textiles and clothing as discussed by the authors is an overview and review of smart textile composites integrated with fibre optic sensors. But it is not a comprehensive review of the entire literature.
Abstract: Smart technology for textiles and clothing - an overview and review. Electrically active polymer materials: application of non-ionic polymer gel and elastomers for artificial muscles. Heat storage and thermo-regulated textiles and clothing. Thermally sensitive materials. Cross-linked polyol fibrous substrates as multifunctional and multi-use intelligent materials. Stimuli-responsive interpenetrating polymer network hydrogels composed of poly(vinyl alcohol) and poly(acrylic acid. Permeation control through stimuli-responsive polymer membrane prepared by plasma and radiation grafting techniques. Mechanical properties of fibre Bragg gratings. Optical responses of FBG sensors under deformations. Smart textile composites integrated with fibre optic sensors. Hollow fibre membranes for gas separation. Embroidery and smart textiles. Adaptive and responsive textile structures (ARTS. Wearable technology for snow clothing. Bio-processing for smart textiles and clothing. Tailor-made intelligent polymers for biomedical applications. Textile scaffolds in tissue engineering.

251 citations