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Proceedings Paper

Temperature and strain characterization of Bragg gratings impressed with femtosecond laser radiation in suspended-silica-core fibers
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Paper Abstract

Fiber Bragg Gratings (FBG's) are widely used in various fields, including optical fiber sensors. In this work, the temperature and strain response of C-band FBG's in pure silica four-leaf clover shaped suspended-core fibers was analyzed. These FBGs were fabricated by femtosecond laser exposure, which enabled the refractive index modulation of the pure-silica-core of the fibers. We compared the Bragg wavelength variation with strain and temperature for two different suspended-core fibers (256b2 and 256b5). The 256b2 fiber has a core diameter of 4,9 μm and a hollow hole inside the core with 1,4 μm; the 256b5 fiber has a solid silica core with a 7,2 μm diameter. For strain and temperature characterization, the sensing head was attached to a translation stage with a resolution of 1 μ;m and was placed in a tubular oven, which permits a temperature reading to be set with an error smaller than 0,1 °C. Both have shown the same sensitivity to strain (1,2 pm/με) but different sensitivity to temperature variation (8,4 pm/°C and 10 pm/°C respectively). The relative difference between the thermal coefficients of the two selected Bragg signatures is 16%. The results obtained indicate that these gratings can be used in optical fiber sensing, for example in the context of the important problem of simultaneous strain and temperature measurement.

Paper Details

Date Published: 4 August 2009
PDF: 8 pages
Proc. SPIE 7386, Photonics North 2009, 73861N (4 August 2009);
Show Author Affiliations
Luís A. Fernandes, INESC Porto (Portugal)
Univ. do Porto (Portugal)
Martin Becker, IPHT Jena (Germany)
Orlando Frazão, INESC Porto (Portugal)
Univ. do Porto (Portugal)
Manfred Rothhardt, IPHT Jena (Germany)
Sven Brückner, IPHT Jena (Germany)
Kay Schuster, IPHT Jena (Germany)
Jens Kobelke, IPHT Jena (Germany)
José L. Santos, INESC Porto (Portugal)
Univ. do Porto (Portugal)
Paulo V. S. Marques, INESC Porto (Portugal)
Univ. do Porto (Portugal)

Published in SPIE Proceedings Vol. 7386:
Photonics North 2009
Réal Vallée, Editor(s)

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