Enhanced sensitivity of transmission based optical fiber hydrogen sensor with multi-layer Pd-Y alloy thin film

The high response rate and sensitivity are the crucial performance parameters of the optical fiber hydrogen sensors when they are used to detect a hydrogen leak. In this paper, a new transmission-type optical fiber hydrogen sensor with multi-layer palladium/yttrium (Pd/Y) alloy films is proposed and experimentally demonstrated to increase the sensitivity of trace hydrogen detected. A special probe structure which has several pieces of Pd/Y alloy films arranged in a line was designed. Since all the films reacted with hydrogen gas simultaneously, this structure not only can respond as quickly as that of only one film but also can increase the influence of films on the light manifold. Then it becomes possible to realize the independent optimization between the response time and sensitivity of hydrogen sensors. The response time can be optimized by the size of the film and the sensitivity can be optimized by the quantity and transmittance of Pd/Y alloy film. This paper provides a new method to research the high performance optical fiber hydrogen sensors.