A Humidity Sensor Based on CFBG Fabry-Perot Interferometer

A fiber-optic humidity sensor by cascading two identical chirped fiber bragg grating (CFBG) to form a Fabry-Perot interferometer (FPI) is proposed and experimentally demonstrated, which is coated with carboxymethyl cellulose sodium (CMC-Na) solution as the humidity sensitive film to achieve the effect of measuring humidity. The sensor has a good linear response of light intensity and wavelength to humidity in the range of 20 %RH-80 %RH, with the sensitivity of 0.1043dB/%RH and 0.0177nm/%RH, respectively. It has a good prospect in the field of humidity sensing and can be widely used in actual humidity measurement.