Distributed beat length measurement in single-mode optical fibers using stimulated Brillouin-scattering and frequency-domain analysis

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.

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“…This was done using the BOFDA method and beat lengths in the range of 50 to 60 m were observed on a 10 km length of fiber [85]. …”

Section: Brillouin Scattering Based Distributed Sensorsmentioning

confidence: 99%

Recent Progress in Distributed Fiber Optic Sensors

Bao

Chen

2012

Sensors

1,112

474

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“…In the frequency domain, the Brillouin optical-fiber frequency-domain analysis (BOFDA) method developed in [23] has used a continuous wave (CW) counterpropagating pump and probe waves to achieve distributed beat length measurement with 5.5 m spatial resolution on an 11 km SMF; however, its maximum sensing range and minimum resolvable distance are limited by the modulation frequency step and the maximum modulation frequency, respectively. Besides, the relatively long measurement time induces extra measurement uncertainty as PMD varies with time.…”

Section: Introductionmentioning

confidence: 99%

Polarization averaged short-time Fourier transform technique for distributed fiber birefringence characterization using Brillouin gain

2012

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A polarization averaged short-time Fourier transform (PASTFT) technique is developed for distributed fiber birefringence characterization based on counterpropagating stimulated Brillouin scattering (SBS) gain signal. This technique can be used for the birefringence characterization of the general elliptical birefringent fiber. A theoretical model on polarization matching of counterpropagating SBS process is established. The performance of the short-time Fourier transform (STFT) method and the PASTFT technique is analyzed by using the simulation of the theoretical model. Simulation results show that the process of polarization average could effectively reduce the birefringence characterization error caused by the polarization dependence of the local period of SBS gain. A less than 8% normalized root mean square error is achieved for the characterization of the length of the birefringence vector on elliptical birefringent fibers. The PASTFT technique is experimentally verified by the distributed measurement of beat length and differential group delay of a standard single-mode fiber via the Brillouin optical time domain analysis system.

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“…The measurement setup is shown in Figure 6. The intensity of pumped and Stokes optical signals (I P and I S ) can be described with the following differential equations [15]:…”

Section: Stimulated Brillouin Scattering Measurementsmentioning

confidence: 99%

Fibre optic sensors based on hollow capillary tube with three tightly encapsulated optical fibres

Basic¹,

Halmetschlager²

2019

Automatika

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Fibre optic sensor cable technology is relatively a new research area that combines a set of scientific and technical disciplines in order to meet distributed sensor system needs and quality standards. In this paper, we discuss a fibre optic sensor design with three tightly encapsulated fibres for multipurpose and multivalent sensing. It has the potential to integrate more detection and measurement techniques into a small space, and this, in turn, largely contributes to installation and cost optimizations and directly impacts investment plans and industrial success. The developed cable is tested in a specially developed high pressure and high temperature chamber. Furthermore, it is demonstrated that the proposed sensor cable offers the possibility of detection and distributed measurement of temperature, pressure, bending and vibrations.

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Distributed beat length measurement in single-mode optical fibers using stimulated Brillouin-scattering and frequency-domain analysis

Cited by 21 publications

References 23 publications

Recent Progress in Distributed Fiber Optic Sensors

Recent Progress in Distributed Fiber Optic Sensors

Polarization averaged short-time Fourier transform technique for distributed fiber birefringence characterization using Brillouin gain

Fibre optic sensors based on hollow capillary tube with three tightly encapsulated optical fibres

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