Simultaneous distributed measurement of strain and temperature from noise-initiated Brillouin scattering in optical fibers

The simultaneous determination of strain and temperature distributions from the measurement of noise-initiated Brillouin scattering (NIBS) power and frequency shift in optical fibers is discussed. Equations governing the growth of the NIBS signal are derived and from these, we calculate the dependen...

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Bibliographic Details
Published in:IEEE journal of quantum electronics 1998-04, Vol.34 (4), p.645-659
Main Authors: Parker, T.R., Farhadiroushan, M., Feced, R., Handerek, V.A., Rogers, A.J.
Format: Article
Language:English
Subjects:
Brillouin scattering
Capacitive sensors
Exact sciences and technology
Frequency
Fundamental areas of phenomenology (including applications)
General equipment and techniques
Instruments, apparatus, components and techniques common to several branches of physics and astronomy
Nonlinear optics
Optics
Physics
Power measurement
Sensors (chemical, optical, electrical, movement, gas, etc.)
remote sensing
Signal to noise ratio
Spatial resolution
Stimulated brillouin and rayleigh scattering
Strain measurement
Temperature dependence
Temperature distribution
Temperature sensors
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Summary:The simultaneous determination of strain and temperature distributions from the measurement of noise-initiated Brillouin scattering (NIBS) power and frequency shift in optical fibers is discussed. Equations governing the growth of the NIBS signal are derived and from these, we calculate the dependence of the Brillouin power on temperature and strain. We study the potential problem given by the need to normalize the nonlinear Brillouin signal and present a new technique that solves this problem by mathematically combining the values of the Stokes and anti-Stokes powers to produce a linear effective power. Experimental results are presented that support this theory and allow the verification of the coefficients governing the dependence of the Brillouin power and frequency shift on temperature and strain. The signal-to-noise ratio of the sensor is discussed, and it is found that the noise associated with the field statistics plays a limiting role in the sensor performance and that an optimum value for the Brillouin gain factor can be determined. A simultaneous distributed temperature and strain sensor is demonstrated; preliminary results show a strain resolution of 100-/spl mu/m strain, a temperature resolution of 4/spl deg/C, and a spatial resolution of 40 m, over a sensing length of 1200 m.
ISSN:0018-9197
1558-1713
DOI:10.1109/3.663443