LPG-based PVA coated sensor for relative humidity measurement

Abstract

A long period grating (LPG)-based optical fiber sensor, coated with polyvinyl alcohol, has been developed for relative humidity (RH) measurement over the range from 33% RH to 97% RH, for which the grating response has been monitored. The fiber optic sensor using the LPG has been designed to monitor the change in resonance loss which is then related to the humidity measured through calibration of the sensor with a series of materials of known refractive index. Results on the calibration and use of the sensor are reported and considered in this work, in light of other grating-based methods for humidity measurement.