Long-lasting phosphorescence in oxygen-deficient Ge-doped silica glasses at room temperature

We report on a novel phenomenon in oxygen-deficient Ge-doped silica glasses at room temperature. Irradiation of focused 120 fs laser pulses at 800 nm induced long-lasting phosphorescence with peaks at 290 and 390 nm for oxyge n-deficient Ge-doped silica glass. The phosphorescence persisted for not le ss than 1 h after the removal of the irradiating light. The intensity of th e phosphorescence at 390 nm increased with an increase in the concentration of oxygen-deficiency associated with Ge ions. Based on the time dependence of the intensity of the phosphorescence, the longlasting phosphorescence i n these glasses is considered to be due to the thermally activated electron -hole recombination at shallow traps. (C) 2001 Elsevier Science B.V. All ri ghts reserved.