Pd/V$_{2}$O$_{5}$ fiber optic hydrogen gas sensor*

The paper presents an optical-fiber hydrogen sensor. The sensor utilizes a layered sensing structure. This structure is a layered Fabry-Perot interferometer and includes gasochromic vanadium pentoxide (V$_{2}$O$_{5})$. A structure is made at the end of multi-mode optical fiber as a sensing element. The sensor permits to detect and to measure the concentration of hydrogen in a gaseous medium. The optical H$_{2}$ gas sensor has a very short response time and a fast regeneration time at room temperature