Photosensitivity and grating writing in hydrogen loaded germanosilicate core optical fibers at 325 and 351 nm

A refractive index grating has been side written in the core of a hydrogen loaded germanosilicate optical fiber using a phase mask and 351 nm light from an Ar ion laser, the longest wave length yet reported, to the best of our knowledge, for a grating of this type. The grating strength was similar to 1.25 dB, indicating an index change of similar to 2 x 10(-4). The fiber was sensitized by low temperature hydrogen loading followed by a brief exposure to a CO2 laser, resulting in the formation of high levels of germanium-oxygen deficiency centers. Fluorescence changes and UV transmission changes in hydrogen loaded germanosilicate glasses exposed to 325 nm and combined 351/364 nm radiation are also reported. (C) 1997 American Institute of Physics.