Effect of gamma–neutron nuclear reactor radiation on the properties of Bragg gratings written in photosensitive Ge-doped optical fiber

Abstract We have experimentally studied the effect of mixed gamma–neutron nuclear reactor radiation on the effective refractive index of Bragg gratings fabricated in Ge-doped photosensitive optical fiber. We compared the effect of radiation on gratings written with and without hydrogen sensitization and show that the use of hydrogen loading results in an increase of the sensitivity to reactor radiation. Neither grating annealing at 500 °C nor pre-irradiation of the fiber results in a significant increase of the radiation hardness of the Bragg gratings. The best radiation stability is observed for gratings fabricated without hydrogen loading.