The photoluminescence color of silica glass changed from weak blue to intense white under irradiation with 325nm laser light at room temperature in vacuum. Irradiation at room temperature with the same laser light under O gas atmosphere erased the white photoluminescence state. By experiment, it was found that the spectral change was a reversible phenomenon. Such intense white photoluminescence state was stored for a long time at room temperature in air under room light after removal of the laser light, in spite of any changes of atmosphere. The observed phenomenon may relate to the photo-induced defect formation at the silica glass surface. Such observed reversible phenomenon may well yield materials for erasable optical information storage, O sensors and white-light emitting devices.

UV-Laser Light-Produced Defects and Reversible Blue–White Photoluminescence Change in Silica. S.Mochizuki, H.Araki: Physica B, 2003, 340-342, 969-73