Blue emission induced in Eu2+-doped glasses by an infrared femtosecond laser

We report on the blue emission in Eu2+-doped aluminosilicate glasses (43CaO:13Al(2)O(3):44SiO(2):0.05Eu(2)O(3): 0.05Nd(2)O(3) and 43CaO:13Al(2)O(3):44SiO(2):0.05Eu(2)O(3)) induced by an infrared femtosecond laser. After the irradiation by an 800 nm 150 fs, 200 kHz laser, the region in which the laser is focused emits blue phosphorescence which is visually detected, in the dark, 10 h after the removal of the activating laser. We suggest that this long lasting phosphorescence is due to the thermal stimulated recombination of holes and electrons at traps induced by the laser irradiation, which leave holes or electrons in a metastable excited state at room temperature. (C) 1999 Elsevier Science B.V. All rights reserved.