Femtosecond Laser Induced Ba2TiSi2O8 Crystal Precipitation in Glass

Ba2TiSi2O8 crystal was space-selectively precipitated in a 33.3BaO-16.7TiO2-50.0SiO2 glass sample by using a high repetition femtosecond laser with 800nm, 150fs and 250kHz. After the femtosecond laser irradiated for a period of time, the luminescence of the focused point could chang from 800nm red light to 400nm blue one due to second-order optical nonlinearity of the precipitated crystal. Raman spectra show Ba2TiSi2O8 crystal is formed. During the femtosecond laser irradiation, heat accumulation effect occurs in the irradiated region by continuously absorbing pulse energy, and the glass would be heated to its crystallization temperature, therefore Ba2TiSi2O8 may grow or precipitate in the crystallized region. Furthermore, the Raman spectra at different positions of the irradiated region demonstrate that Ba2TiSi2O8 crystal grows more effectively in the center compared with that in the outers. This result is agreeable with the femtosecond lasera2induced temperature distribution because the temperature increases more quickly in the focused region.