Optical Fiber Hydrogen Sensor Based on Magnetron Sputtered Pd/V<sub>2</sub>O<sub>5</sub> Films

Abstract

Laminated thin films composed of V2O5 and Pd (or Pt-Pd) layers were deposited on glass substrates and the end faces of multimode optical fibers, and the sensitive behaviors of the thin films to hydrogen gas were studied using a UV-visible spectrophotometer and an optical fiber sensor’s experimental setup. Both the thickness of the V2O5 layer and that of the Pd layer have obvious influences on the sensitivity performance of the Pd/V2O5 films. The Pd (30 nm)/V2O5 (280 nm) film deposited on a glass substrate is sensitive to 0.1% hydrogen and the highest change in relative transmittance is about 25% when exposed to 4% hydrogen. Pd/V2O5 films were coated onto the end faces of multimode fibers to form optical fiber sensors. The response time of the Pd (20 nm)/V2O5 (280 nm) sensor is about 50 s and the change in relative reflected light intensity is about 18% upon exposure to 4% hydrogen. Deposition of Pt-Pd double layer instead of Pd signal layer over V2O5 can reduce the response time of the sensor. The response time of the Pd (20 nm)/V2O5 (280 nm) sensor is about 50 s, while that of the Pt (10 nm)-Pd (10 nm)/V2O5 (280 nm) sensor is about 25 s.