UV-laser-light-produced defects and reversible blue-white photoluminescence change in silica

The photoluminescence (PL) color of silica glass changes from weak blue to intense white under irradiation with 325 nm laser light at room temperature in vacuum. Irradiation at room temperature with the same laser light under oxygen gas atmosphere erases the white PL state. Through many successive experiments, it is found that the spectral change is a reversible phenomenon. Such intense white PL state is 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, oxygen sensors and white-light emitting devices