Hydrogen influence on Brillouin and Rayleigh distributed temperature or strain sensors

Distributed optical fiber sensors are a clue technology for the monitoring of geological repository for long-lived nuclear wastes. Environment includes hydrogen whose influence on Rayleigh and Brillouin scatterings is experimentally evaluated. Induced propagation losses are quantified, as a function of wavelength and fiber dopants. 1310nm resulted the most favorable working wavelength. Distance range would anyway be reduced down to a hundred meter. We show hydrogen also induces Brillouin frequency shifts, up to 21MHz which corresponds to large temperature and strain measuring errors if not corrected. Fluorine fibers appeared more sensitive for short hydrogen exposure than other tested fibers.