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Proceedings Paper

Optical fibre relative humidity sensor based on a hydrogel coated long period grating
Author(s): Xiujuan Yu; Liwei Wang; Jintao Zhang; Min Zhang; Shengchun Liu; Yanbiao Liao
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Paper Abstract

A hydrogel coated long period grating (LPG) used as relative humidity sensor is investigated theoretically and experimentally. It showed a high degree of sensitivity when relative humidity was above 50%RH. For humidity levels from 50%RH to 72%RH, a wavelength decrease of 15.4 nm is seen, with a sensitivity of 0.66 nm /%RH. For humidity levels from 72%RH to 98%RH, a wavelength increase of 9.5nm is observed, with a sensitivity of 0.36 nm /%RH. For humidity levels greater than 65%RH, the transmission loss at resonance increases rapidly, showing a high degree of sensitivity of 0.53 dB /%RH and offering a high resolution of 0.02%RH. The proposed relative humidity sensor offered good repeatability and low hysteresis errors, with a standard deviation of 0.005dB/%RH and 0.26% hysteresis error while RH levels greater than 65%RH during three cycles of increasing and decreasing humidity. The stability test was also carried out and a standard deviation of 0.14%RH was obtained. In addition, the durability test showed that the humidity sensor can work at least ten months.

Paper Details

Date Published: 22 November 2011
PDF: 9 pages
Proc. SPIE 8199, 2011 International Conference on Optical Instruments and Technology: Optical Sensors and Applications, 81990W (22 November 2011); doi: 10.1117/12.904716
Show Author Affiliations
Xiujuan Yu, Heilongjiang Univ. (China)
Liwei Wang, Tsinghua Univ. (China)
Jintao Zhang, Heilongjiang Univ. (China)
Min Zhang, Tsinghua Univ. (China)
Shengchun Liu, Heilongjiang Univ. (China)
Yanbiao Liao, Tsinghua Univ. (China)

Published in SPIE Proceedings Vol. 8199:
2011 International Conference on Optical Instruments and Technology: Optical Sensors and Applications
Brian Culshaw; YanBiao Liao; Anbo Wang; Xiaoyi Bao; Xudong Fan, Editor(s)

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