Study of the hydrogen influence on the acoustic velocity of single-mode fibers by Rayleigh and Brillouin backscattering measurements

摘要

We study the effect of hydrogen gas diffusion in silica optical fibers on Brillouin and Rayleigh scatterings. By modeling hydrogen diffusion kinetics as a function of temperature and pressure and by measuring simultaneously Rayleigh and Brillouin scattering on G652 single-mode fiber samples during H_2 desorption (previously exposed to 175 bars H_2 at 80°C), we have demonstrated experimentally that acoustic velocity increases linearly with H_2 concentration with a ratio of about (4.8 m/s) / (%mol H_2).