Correlation between oxygen-deficient center concentration and KrF excimer laser induced defects in thermally annealed Ge-doped optical fiber preforms

The amplitude of the 5 eV optical absorption band of oxygen-deficient germa nium-doped silica samples (3GeO(2):97SiO(2)) was varied by annealing in oxy gen at 1000 degrees C for different periods of time. Each sample was irradi ated with the same dose of 5 eV light from a KrF excimer laser to study the effect of the absorption band amplitude on the photo-induced changes. ESR (Electron spin resonance) and optical absorption measurements were carried out after each annealing and each laser irradiation cycle. We find that sam ples with an initially higher 5 eV absorption band amplitude exhibit a larg er increase in the absorption bands related to the photo-induced paramagnet ic Ge E' and GEC (Germanium Electron Center) when irradiated with the same laser dose. Deconvolution of the measured spectra shows that the concentrat ions of the photo-induced paramagnetic Ge E' and GEC defects are well corre lated with the concentration of GLPC (germanium lone pair center) defects a ssociated with a 5.14 eV absorption band. (C) 1999 Published by Elsevier Sc ience B.V. All rights reserved.