Abstract
Relative humidity monitorization is of extreme importance on scientific and industrial applications, and fiber optics-based sensors may provide solutions where other types of sensors have limitations. In this work, fiber optics’ sensors were fabricated by combining Long-Period Fiber Gratings with three different humidity-responding polymers, namely Poly(vinyl alcohol), Poly(ethylene glycol) and Hydromed™ D4. The performance of the multiple sensors was experimentally tested and crossed with numerical simulations, which provide a comparison with the expected response given the optical properties of the materials.
Highlights
The real time monitoring of relative humidity on scientific and industrial applications is of extreme importance and many types of sensors have been developed, mostly based on capacitive or resistive structures which may display some flaws, such as not being immune to electromagnetic radiation, and not fit to extreme and harsh environments
This allowed the calibration of the wavelength shift and optical power shift induced by the coating process, meaning that for a given long-period fiber gratings (LPFG) it is possible to choose the concentration of the coating solution that gives both visibility of the rejection band and high sensitivity to the RH variation
Given that the RH response of the sensor is a result of changes in refractive index (RI) and the thickness of the coating layer, testing LPFGs coated with solutions of different concentrations will allow exploration of different responses caused by this variation of parameters
Summary
The real time monitoring of relative humidity on scientific and industrial applications is of extreme importance and many types of sensors have been developed, mostly based on capacitive or resistive structures which may display some flaws, such as not being immune to electromagnetic radiation, and not fit to extreme and harsh environments (such as underwater applications). The polymers display a refractive index (RI) that decreases with the absorption of water molecules, displaying considerable swelling effects. These changes can be tracked by analyzing the spectral characteristics of specific optical structures such as long-period fiber gratings (LPFG) [5,6]. LPFGs consist of a periodic modulation to the RI of the core of the fiber, resulting in coupling of light from the fundamental core mode to the co-propagating cladding modes, which creates rejection bands in the transmission spectrum at specific wavelengths with high sensitivity to the surrounding RI.
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.
