Optical Fiber Hydrogen Sensors with Pd/W03 Composite Thin Film by Magntron Co-Sputtering

A fiber-optic hydrogen gas sensor using composite palladium and tungsten trioxide (WO₃) was proposed and characterized. This sensor utilizes the absorption of the evanescent field interaction in the clad of Pd/WO₃ thin film which was prepared by magnetron co-sputtering process, coated on a silica core. Modulation of optical power intensity is observed, a clear increase of power with hydrogen and decrease of power without hydrogen can be concluded. Compared to pure Pd sensitive material, an improvement of response time is reported. Meanwhile, there is no recovery in nitrogen environment, and recovery happens only in oxygen-existing condition. It is suspected that the recovery process is connected to oxidation of the Pd/WO₃ surface.