Optical fibers are used routinely in harsh environments for signal transmission or sensing applications . Whereas the individual challenges originating from very high or very low temperatures, vacuum or ionizing radiation were extensively studied, the effects of combinations of these conditions were not investigated widely.
The radiation sensitivity of Bragg gratings written with a femtosecond IR laser was measured for the first time.
Type I-IR and type II-IR gratings were written into hydrogen loaded as well as unloaded fibers of distinctly different
radiation sensitivity with the intention to find extremely radiation resistant gratings for temperature or stress
measurements in radiation environments, as well as very radiation sensitive ones for radiation dose measurements. With
a highly radiation-hard F-doped fiber we found a radiation-induced wavelength shift between about 3 and 7 pm after a
dose of 100 kGy. These are the lowest shifts observed so far. In such fibers it is very difficult to write gratings with an
UV laser. However, gratings made of the highly radiation-sensitive fibers only showed shifts of about the same size as
those made of the quite radiation-insensitive Corning SMF-28e fiber. This was already observed with UV laser gratings
written in such fibers.