title: Polyvinyl alcohol-coated hybrid fiber grating for relative humidity sensing.
abstract: A relative humidity (RH) sensor based on a hybrid fiber grating coated with polyvinyl alcohol is proposed and demonstrated experimentally. The hybrid fiber grating is formed by superimposing a normal fiber Bragg grating (FBG) and a tilted-FBG around the same position of a single-mode fiber so that it can work in the reflection mode. Optical power of the reflected signal changes with the refractive index of the moisture sensitive polyvinyl alcohol, and humidity measurement can be realized. Experimental results show that the measurement range is 30 to 95% with the maximum sensitivity of 0.737 nW∕% RH. The average response time is ∼2 s and the measurement is nearly insensitive to temperature. Compared with the wavelength detection method used in normal FBG-based relative humidity sensors, the intensity demodulation method in this report is simpler and more cost-efficient.
authors.affiliation: China Jiliang University, Institute of Optoelectronic Technology, Hangzhou, China, 310018. xydong@cjlu.edu.cn
authors.forename: Xinyong
authors.initials: X
authors.lastname: Dong
authors.forename: Tao
authors.initials: T
authors.lastname: Li
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.forename: Yi
authors.initials: Y
authors.lastname: Li
authors.forename: Chun-Liu
authors.initials: CL
authors.lastname: Zhao
authors.forename: Chi Chiu
authors.initials: CC
authors.lastname: Chan
mesh_terms: D006813:Humidity; D055100:Optical Fibers; D011142:Polyvinyl Alcohol; D012031:Refractometry
chemical_list: D011142:Polyvinyl Alcohol