Direct observation of UV induced bleaching of 240 nm absorption band in photosensitive germanosilicate glass fibres

Abstract

Ultraviolet loss measurements on germanosilicate fibre samples showing an intense absorption, centred at 242 nm, with an associated fluorescence at 413 nm are presented. The first direct observation is reported of the bleaching of this 240 nm band under the action of ultraviolet irradiation, evidence which is consistent with the Kramers-Kronig model for the photosensitive refractive index change in these glasses.