Gamma-Radiation Effects on Bragg Gratings Written by Femtosecond UV Laser in Ge-Doped Fibers

We studied the effect of Co60 gamma-radiation on the position and the amplitude of fiber Bragg gratings. These gratings were written with a femtosecond UV laser in three different fibers, both intrinsically photosensitive and hydrogen sensitized.We have found that in contrast with the results obtained on gratings written with low-intensity UV lasers, the Bragg peak shift under irradiation is almost independent on fiber type, fiber sensitization or grating amplitude. The grating strength behavior depends on the fiber type.