Humidity Sensor Based on a Long-Period Fiber Grating Coated with Polymer Composite Film

Yunlong Wang; Yunqi Liu; Fang Zou; Chen Jiang; Chengbo Mou; Tingyun Wang

doi:10.3390/s19102263

Humidity Sensor Based on a Long-Period Fiber Grating Coated with Polymer Composite Film

Sensors (Basel). 2019 May 16;19(10):2263. doi: 10.3390/s19102263.

Authors

Yunlong Wang¹, Yunqi Liu², Fang Zou^{3

4}, Chen Jiang⁵, Chengbo Mou⁶, Tingyun Wang⁷

Affiliations

¹ Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication, Shanghai Institute for Advanced Communication and Data Science, Shanghai University, Shanghai 200444, China. lightsmile@shu.edu.cn.
² Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication, Shanghai Institute for Advanced Communication and Data Science, Shanghai University, Shanghai 200444, China. yqliu@shu.edu.cn.
³ Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication, Shanghai Institute for Advanced Communication and Data Science, Shanghai University, Shanghai 200444, China. ZF-198166@sohu.com.
⁴ Department of Information Engineering, Hebei GEO University, Shijiazhuang 050031, China. ZF-198166@sohu.com.
⁵ Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication, Shanghai Institute for Advanced Communication and Data Science, Shanghai University, Shanghai 200444, China. jiangchen17@shu.edu.cn.
⁶ Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication, Shanghai Institute for Advanced Communication and Data Science, Shanghai University, Shanghai 200444, China. mouc1@shu.edu.cn.
⁷ Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication, Shanghai Institute for Advanced Communication and Data Science, Shanghai University, Shanghai 200444, China. tywang@shu.edu.cn.

Abstract

We demonstrate a simple and highly sensitive optical fiber relative humidity (RH) sensor based on a long-period fiber grating (LPFG) coated with polyethylene glycol (PEG)/polyvinyl alcohol (PVA) composite films. The resonance wavelength of the LPFG is sensitive to environmental humidity due to the change in effective refractive index caused by the strong surface absorption and desorption of the porous PEG/PVA coatings. The sensor is sensitive in a wide range from 50% to 95% RH, with a highest sensitivity of 2.485 nm/%RH in the range 50-75% RH. The proposed RH sensor has the advantages of compact size, good reversibility, and stability, which makes it attractive for high-humidity environments.

Keywords: PEG; PVA; humidity sensor; long-period fiber grating (LPFG); polymer coating.

Abstract

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