A miniaturized fiber tip Fabry-Perot interferometer (FPI) with Pt/WO<sub>3</sub> coating was demonstrated as a hydrogen sensor.
The air-cavity of FPI was formed by inserting a single mode fiber (SMF) into a partially polymer-filled glass capillary,
which was highly sensitive to temperature. A layer of Pt/WO<sub>3</sub> was coated on the glass capillary of the FPI serving as a reaction heater upon hydrogen exposure. The heat locally raised the FPI temperature, which led to the wavelength shift of interference spectrum. The average wavelength shift of two interference dips was -20.3 nm upon exposure to ~20000 ppm hydrogen concentration. The hydrogen sensitivity of the sensor was estimated to be better than 1 pm/ppm.
A novel method was proposed to improve hydrogen sensitive performance of fiber Bragg grating (FBG) hydrogen sensor. The hydrogen performance of the sensor can be greatly improved by combing Pt/WO3 composite film annealed under 315°C for 1 h and temperature sensitive FBG. At room temperature of 25°C, FBG coated with Pt/WO3 composite film has 536 pm wavelength shift towards 10000 ppm hydrogen, and hydrogen detection threshold of FBG hydrogen sensor can reach to 200 ppm. The hydrogen performance of FBG hydrogen sensor was studied under different humidity, and ambient humidity has little effect on the hydrogen performance of FBG hydrogen sensor.