  We investigated the effect of continuous-wave (cw) UV laser radiation on
single-mode Ge-doped H2- loaded optical fibers. An innovative technique was
developed to measure the optical absorption (OA) induced in the samples by
irradiation, and to study its dependence from laser fluence. The combined use
of the electron spin resonance (ESR) technique allowed the structural
identification of several radiation-induced point defects, among which the
Ge(1) (GeO4 -) is found to be responsible of induced OA in the investigated
spectral region.
