Energetic radiation influence on temperature dependency of Brillouin frequency in optical fibers
Résumé
Brillouin scattering in optical fibers is one of the most suitable tools for Structural health monitoring. Its sensitivity to strain and temperature [1] and the ability to perform distributed measurement over long ranges have placed Brillouin sensors at the forefront of sensing application. Nevertheless, in nuclear waste storage facility monitoring, radiation (X, gamma, neutron ...) influence should be taken in consideration. It is well-know that propagation losses will increase, with a rate depending on fiber dopants, temperature, laser power etc [3][4]. As Brillouin sensors rely on frequency variations, expected intensity variation should only degrade signal to noise ratio. Recently, we observed a 20MHz permanent change in the Brillouin frequency (at 1.55µm) in photosensitive germanosilicate optical fibers after an energetic radiation exposure [2]. We now wonder about the energetic radiation influence on the Brillouin frequency shift dependency on the temperature change. To our knowledge it is the first study of the possible radiation influence on Brillouin frequency shift dependency on temperature.