OPTICALLY-ACTIVE OXYGEN-DEFICIENCY-RELATED CENTERS IN AMORPHOUS-SILICON DIOXIDE

The spectroscopic properties, structure and interconversions of optica lly active oxygen-deficiency-related point defects in vitreous silica are reviewed. These defects, the E'-centers (oxygen vacancies with a t rapped hole or 3-fold-coordinated silicons), different variants of dia magnetic ''ODCs' (oxygen-deficiency centers), and their Ge-related ana logs play a key role in the fiber-optic Bragg grating writing processe s. The controversy surrounding the structural models for the Si- and G e-related ODCs is discussed and the similarity between the bulk and su rface point defects in silica is emphasized. The possible interconvers ion mechanisms between 2-fold-coordinated Si, neutral oxygen vacancies and E'-centers are discussed. The effects of glassy disorder have a p rofound effect on defect properties and interconversion processes in s ilica, (C) 1998 Elsevier Science B.V. All rights reserved.