title: Fiber-optic cavity sensing of hydrogen diffusion.
abstract: A novel type of fiber-optic cavity sensor for hydrogen diffusion into and out of fibers is presented. The sensor is an implementation of a cavity ringdown scheme in a silica-based single-mode fiber that has been exposed to gaseous hydrogen at normal pressure. The measured ringdown times during the H2 diffusion show good agreement with a theoretical diffusion model. This model allows the determination of the diffusion coefficient of hydrogen in silica, resulting in D = (3.02 +/- 0.07) x 10(-15) m2/s at 30 degrees C.
authors.affiliation: Swiss Federal Institute of Technology (ETH), Institute of Quantum Electronics, Laser Spectroscopy and Sensing Laboratory, Hoenggerberg HPF D23, CH-8093 Zurich, Switzerland. vogler@iqe.phys.ethz.ch
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Vogler
authors.forename: Michel G
authors.initials: MG
authors.lastname: Müller
authors.forename: Markus W
authors.initials: MW
authors.lastname: Sigrist