Infrared Femtosecond Laser Induced Visible Long-Lasting Phosphorescence in Mn2+-Doped Sodium Borate Glasses

Abstract

We report on the long-lasting phosphorescence phenomenon in Mn²⁺-doped sodium borate glass. After scanning by a focused 800 nm femtosecond laser for 10 s, the path traversed by the focal point of the laser in the glass emits reddish long-lasting phosphorescence visible to the naked eye in the dark five minutes after the removal of the activating laser. Absorption spectra of the glass showed that defect centers were induced after laser irradiation, and the absorption due to the laser-induced defect centers decayed with time. The long-lasting phosphorescence is considered to be due to the thermostimulated recombination of holes and electrons at traps induced by the laser irradiation, and energy transfer from the composite defect centers to Mn²⁺ ions.