Humidity Sensor Based on Fiber Grating Coated with Graphene Oxide

Abstract

Graphene oxide (GO) is a new two-dimensional carbon nano-material with large specific surface area and outstanding hydrophilicity. Its refractive index varies significantly with humidity, which can be used to improve the sensitivity of optical fiber humidity sensor. A kind of fiber Bragg grating (FBG) humidity sensor based on GO is proposed and experimentally demonstrated. GO is uniformly coated on the FBG surface by deposition. When the ambient humidity changes, the GO film adsorbs or releases water molecules and its refractive index changes. Thus the effective refractive index of FBG changes and the transmission wavelength also changes. The experimental results show that the sensor has a linear response of 2.53 pm/% RH in the range of 20%-70% RH, so it has the advantages of high sensitivity and simple structure.