Photostimulated long-lasting phosphorescence in rare-earth-doped glasses

We report on the observation of photostimulated long-lasting phosphorescence in a Tb3+-doped glass sample. After irradiation by an ultraviolet (UV) light at 254 nm or an 800 nm femtosecond pulsed laser, we find that the glass sample emits bright and long-lasting phosphorescence. Long-lasting phosphorescence is observed once again after further excitation by 365 nm UV light when the 254 nm UV light or the femtosecond laser-induced long-lasting phosphorescence cannot be detected. The intensity of the photostimulated long-lasting phosphorescence decreases in inverse proportion to the time. Based on absorption, emission spectra and thermoluminescence curves, we consider the photostimulated long-lasting phosphorescence to be due to the light-induced re-arrangement and thermostimulated recombination of electrons and holes in traps induced by the 254 nm UV light or the femtosecond laser at room temperature. We infer that the observed phenomenon is useful in the fabrication of rewriteable three-dimensional optical memory with ultrahigh storage density and ultrafast storage speed.