Defect radial repartitions in ultraviolet irradiated germanosilicate optical fibres

We report experimental results about defects induced by ultraviolet light i n germanosilicate optical fibres excited with argon laser light (457.9, 488 and 514.5 nm). A spatial filtering technique was developed and it allows u s to separate the fibre core defects from those in the fibre cladding. The emission spectra show, unambigously, that some preexisting defects located in the fibre core are not sensitive to the ultraviolet irradiation while se veral kinds of photo-induced defects (Ge and Si oxygen deficient centres, g ermanium drawing induced defects and non bridging oxygen hole centres) are created in the fibres. (C) 1999 Elsevier Science B.V. All rights reserved.