LASER-INDUCED DARKENING IN THIN FILMS OF FLUORESCEIN-DOPED BORIC ACID GLASS

摘要

We report laser-induced permanent darkening in thin films of fluorescein-doped boric acid glass. The photodarkening is accompanied by a substantial increase in the absorption of the irradiated samples. The photoinduced absorption appears to be permanent. Optical and electron paramagnetic resonance measurements suggest the creation of a new photochemical species on irradiation within the absorption band of the fluorescein molecule. A possible mechanism for the photochemical change responsible for the darkening is proposed. Optical storage of information through the formation of permanent holograms is demonstrated. (C) 1996 Optical Society of America [References: 14]