Abstract
We report on photochemical hole burning of Sm2+ in sodium borate glasses irradiated with femtosecond-laser pulses of 800nm wavelength. The irradiation of Sm3+-doped sodium borate glasses with femtosecond-laser pulses causes electron-trapped Sm3+, i.e., Sm2+ and point defects such as an oxygen hole center and an electron trapped near Na+. The measurements of spectral hole burning were carried out for the 5D0-7F0 transition of Sm2+ using a DCM dye laser. Photoionization hole burning is observed at 77K to room temperature for the glasses exposed to femtosecond-laser pulses, and also for the glasses prepared by melting under reducing conditions. The hole-burning efficiency of Sm2+ produced by the photoinduced process is about twice higher than that by the thermal process. It is thought that the metastable Sm2+ ions and oxygen hole centers induced by femtosecond-laser irradiation are responsible for the observed phenomenon. We propose that the efficient photoionization hole burning is caused by the photostimulated recombination of the electron trapped by Sm3+ with the oxygen hole center.
