Optical cascaded Fabry–Perot interferometer hydrogen sensor based on vernier effect

Abstract An optical cascaded Fabry–Perot interferometer hydrogen sensor based on vernier effect has been proposed and achieved. The proposed sensor, which total length is ∼ 594 μ m, is composed of a segment of large mode area fiber (LMAF) and a segment of hollow-core fiber (HCF). The proposed sensor is coated with the Pt-loaded WO 3 /SiO 2 powder which will result in the increase of local temperature of the sensor head when exposed to hydrogen atmosphere. Thus the hydrogen sensor can be achieved by monitoring the change of resonant envelope wavelength. The hydrogen sensitivity is −1.04 nm/% within the range of 0 % –2.4 % which is greatly improved because of the vernier effect. The response time is ∼ 80 s. Due to its compact configuration, the proposed sensor provides a feasible and miniature structure to achieve detection of hydrogen.