Paramagnetic germanium-related centers induced by energetic radiation in optical fibers and pre-forms

We investigated the creation processes of Ge-related paramagnetic point defects in silica fibers and pre-forms, doped with different amounts of germanium, and X-ray irradiated at several radiation doses. Different paramagnetic defect species like Ge', Ge(1) Ge(2) were revealed by electron paramagnetic resonance measurements and their concentration was studied as a function of the irradiation dose. The comparison with the optical absorption spectra points out the main role of Ge(1) on the optical transmission loss of fibers in the UV region. (authors)