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Proceedings Paper

Relative humidity sensor based on long period grating with agarose gel coating
Author(s): Yan Liu; Xiang Huang; Bo Liu; Yinping Miao; Hao Zhang; Xingya Chen
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Paper Abstract

A long period grating (LPG) with agarose gel coating has been developed for relative humidity (RH) monitoring for first time. Increase of RH will result in volume expansion and refractive index increment of the agarose gel cladding coating. Since the LPG is sensitive to applied strain and ambient refractive index, the spectral properties of agerose-gel-coated LPG changes accordingly as the ambient humidity levels ranges from 25% to 95% RH. Both the resonance wavelength and coupling strength turn out particular responses to RH for two different RH ranges (25%-65% RH and 65%-95% RH). The coupling strength decreases within a lower RH range while increases throughout a higher RH range. The resonance wavelength is sensitive to RH only for higher RH levels, and the highest sensitivity reaches 108.67 pm/% RH, sharing a same RH turning point with coupling strength response. From a practical perspective, the proposed RH sensor would find its potential applications in temperature-independent RH sensing and multi-parameter sensing based on wavelength/power hybrid interrogation and even static RH alarm for automatic monitoring of a fixed RH value owing to its non-monotonic RH dependence of the transmission power within the whole tested RH range.

Paper Details

Date Published: 30 November 2011
PDF: 8 pages
Proc. SPIE 8201, 2011 International Conference on Optical Instruments and Technology: Optoelectronic Measurement Technology and Systems, 820109 (30 November 2011); doi: 10.1117/12.906647
Show Author Affiliations
Yan Liu, Nankai Univ. (China)
Xiang Huang, Nankai Univ. (China)
Bo Liu, Nankai Univ. (China)
Yinping Miao, Tianjin Univ. of Technology (China)
Hao Zhang, Nankai Univ. (China)
Xingya Chen, Nankai Univ. (China)


Published in SPIE Proceedings Vol. 8201:
2011 International Conference on Optical Instruments and Technology: Optoelectronic Measurement Technology and Systems
Xinyong Dong; Xiaoyi Bao; Perry Ping Shum; Tiegen Liu, Editor(s)

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