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.
Highlights
Relative humidity (RH) is an important magnitude in many fields, such as agricultural production, food storage, pharmaceuticals, health monitoring, and meteorological services
We demonstrate a highly sensitive humidity sensor based on a CO2 -laser-written
Since the glass U-groove filled with the polyethylene glycol (PEG)/polyvinyl alcohol (PVA) mixed solution was horizontally placed in the drying oven and the solute was uniformly dispersed in the solution, the evaporation of water molecules was a slowly and evenly changing process
Summary
Relative humidity (RH) is an important magnitude in many fields, such as agricultural production, food storage, pharmaceuticals, health monitoring, and meteorological services. Much attention has been paid on optical fiber humidity sensors [1,2] due to their advantages such as ease of fabrication, light weight, remote measurement, high sensitivity, and most importantly, electromagnetic immunity. As for wavelength-based techniques, the transmission spectrum can be used to monitor the RH change of the environment Several structures, such as cladding-etched optical fiber [6], side-polished fiber [7], fiber. Bragg grating [8,9,10], Fabry–Perot interference [11], and long-period fiber grating (LPFG) [12,13] have been proposed These structures usually have a transmission dip at a specific wavelength, which could be used to measure the surrounding refractive index (SRI).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
