Fiber Optic Humidity Sensor Based on Michelson Interferometer Coated with Composite Film

A humidity sensor based on a thin-core fiber Michelson interferometer coated with humidity-sensitive composite material is proposed. The humidity sensing characteristics of fiber Michelson interferometer coated with different proportions of HA/PVA films are investigated. The experimental results show that the interferometer coated with 1:2
$HA/PVA$
has the best overall performance, and the wavelength sensitivity is 0.1679nm/%RH in the range of 50
^%
RH--80
^%
RH and the temperature cross sensitivity is O.07
^%
RH/°C. The proposed optical fiber humidity sensor has the merits of high sensitivity, good linearity and low hysteresis.