Photostimulable Luminescence Glasses as a Novel Material for Optical Memory

We report on photostimulated luminescence in sodium borate glasses doped with Eu2+ (Ce3+) and Sm3+. When X-ray or 266 nm UV laser irradiated glasses were excited by a He–Ne laser (633 nm), photostimulated luminescence at 470 nm for Eu2+-doped glass and at 360 nm for Ce3+-doped glass due to the 5d-4f transition of Eu2+ and Ce3+ was observed. X-ray absorption spectra of glasses, X-ray irradiated for various durations and photostimulated excitation spectra were measured. On comparing with the mechanism of photostimulated luminescence in BaFBr:Eu2+, the luminescence is proposed to have resulted from the photostimulated recombination of holes and electrons at traps, which leave the electrons in a long-lived excited state. These glasses can be used as materials for read once and write many optical memories, which is considered to be important for the protection of certain types of software.