A novel fiber humidity sensor is presented and experimentally demonstrated

which is composed of Mach-Zehnder interferometer（MZI） by splicing no-core fiber with single mode fiber

and then coated with gelatin film on the cladding surface of no-core fiber by pull method.The experimental results show that the relative humidity is measured by demodulating the shift of the wavelength of the resonant peak of the transmission spectrum of the sensor.The sensor is very sensitive to high humidity.The sensor has fast response to humidity

sensitivity to ambient temperature

and low cross sensitivity to humidity measurement.The proposed sensor has simple structure

low cost

easy fabrication

high sensitivity and fast response

and has certain application value in engineering practice.