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 oftrace 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.