Gamma-radiation effects on the femto-second fiber Bragg gratings written in Ge-doped fibers

We studied the effect of Co 60 gamma-radiation on the peak position and the amplitude of fiber Bragg gratings. The gratings were written with a femto-second UV laser in three different fibers, both intrinsically highly photosensitive and hydrogen sensitized. We have found that in contrast with the results obtained on gratings written with UV-lasers, the Bragg peak shift under radiation is almost independent on the fiber type, the use of hydrogen loading, or grating amplitude. The grating amplitude change depends on the fiber type.