Hydrogen leak optical sensor using radiating fiber gratings

The explosion risk linked to the use of hydrogen (H₂) as combustible requires low-cost and efficient sensors. We present an optical fiber sensor capable of H₂ leak detection as low as 1% concentration in air with a response time smaller than a few seconds. Our solution makes use of long period fiber gratings (LPFGs) surrounded by a catalytic sensitive layer made of a ceramic doped with a noble metal. On the sensitive layer, H₂ undergoes in air an exothermic reaction and elevates the temperature around the LPFGs. The sensor interrogation technique is based on the monitoring of the resonant wavelength shift. In this paper, the performances of the sensor are discussed.