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Proceedings Paper

The spectral sensitivity of long-period gratings fabricated in elliptical core D-shaped optical fiber
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Paper Abstract

Long period gratings (LPGs) were written into a D-shaped optical fibre, which has an elliptical core with a W-shaped refractive index profile. The LPG's attenuation bands were found to be sensitive to the polarisation of the interrogating light with a spectral separation of about 15nm between the two orthogonal polarisation states. In addition, two spectrally overlapping attenuation bands corresponding to orthogonal polarisation states were observed; modelling successfully reproduced this spectral feature. The spectral sensitivity of both orthogonal states was experimentally measured with respect to temperature, surrounding refractive index, and directional bending. These LPG devices produced blue and red wavelength shifts of the stop-bands due to bending in different directions. The measured spectral sensitivities to curvatures, dλ/dR, ranged from -3.56nm m to +6.51nm m. The results obtained with these LPGs suggest that this type of fibre may be useful as a shape/bend sensor. It was also demonstrated that the neighbouring bands could be used to discriminate between temperature and bending and that overlapping orthogonal polarisation attenuation bands can be used to minimise error associated with polarisation.

Paper Details

Date Published: 14 December 2004
PDF: 12 pages
Proc. SPIE 5589, Fiber Optic Sensor Technology and Applications III, (14 December 2004); doi: 10.1117/12.569312
Show Author Affiliations
Thomas D.P. Allsop, Aston Univ. (United Kingdom)
Tim Earthrowl, Aston Univ. (United Kingdom)
Helen Dobb, Aston Univ. (United Kingdom)
Vladimir Mezentsev, Aston Univ. (United Kingdom)
Andrew M. Gillooly, Aston Univ. (United Kingdom)
David J. Webb, Aston Univ. (United Kingdom)
Ian Bennion, Aston Univ. (United Kingdom)

Published in SPIE Proceedings Vol. 5589:
Fiber Optic Sensor Technology and Applications III
Michael A. Marcus; Brian Culshaw; John P. Dakin, Editor(s)

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