Direct writing three-dimensional Ba2TiSi2O8 crystalline pattern in glass with ultrashort pulse laser

The nonlinear optical crystal Ba2TiSi2O8 is induced three-dimensionally inside a glass by a femtosecond pulse laser with 800nm, 250kHz, and 150fs. Micro-Raman and photoluminescence spectra confirm that crystals can grow in the focal point of the laser beam. Continuous crystalline lines were written through moving the focal point of the laser beam inside the glass. The results demonstrate a convenient method to engrave three-dimensional patterns of crystals with nonlinear optical properties for integrated optical devices.