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Proceedings Paper

Long-period fiber grating curvature sensor based on temperature-insensitive wavelength separation measurements
Author(s): Yunqi Liu; Mei Nar Ng; Kin Seng Chiang; Jianping Yao
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Paper Abstract

Long period fiber gratings (LPFGs) have important applications in fiber sensors because of their high sensitivity to temperature, strain, and refractive index of surrounding medium, et al. In this paper, we demonstrate the bending-induced resonance mode splitting of the LPFG in three different photosensitive fibers (QPS-T)fiber, O/E Land fiber and Fiber Core fiber). For the QPS-T photosensitive fiber, when the grating is bent, the resonant dip shifts to a longer wavelength with a reduction in strength and a new dip emerges at a shorter wavelength. The wavelength separation between the new dip and the original one is linear with the deflection of the grating. The similar results are also observed in two other LPFGs. But when the grating is bent, the original dip of grating shifts to a shorter wavelength and the new dip shift to longer wavelength. The different bending properties of the LPFGs are observed in the different photosensitive fiber, which is attributed to the different fiber parameters. For the LPFG written in the QPS fiber, the bending and temperature properties of the dip corresponding to the LP09 mode is studied experimentally. Based on the property that the new dip induced by the bending of fiber has the same temperature sensitivity with the original one, a temperature-insensitive curvature sensor is proposed by measuring the wavelength separation of the two dips.

Paper Details

Date Published: 30 October 2001
PDF: 6 pages
Proc. SPIE 4596, Advanced Photonic Sensors and Applications II, (30 October 2001); doi: 10.1117/12.447331
Show Author Affiliations
Yunqi Liu, Nanyang Technological Univ. (Singapore)
Mei Nar Ng, City Univ. of Hong Kong (Hong Kong)
Kin Seng Chiang, City Univ. of Hong Kong (Hong Kong)
Jianping Yao, Nanyang Technological Univ. (Canada)

Published in SPIE Proceedings Vol. 4596:
Advanced Photonic Sensors and Applications II
Anand Krishna Asundi; Wolfgang Osten; Vijay K. Varadan, Editor(s)

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