Size-controlled oriented crystallization in SiO_2-based glasses by femtosecond laser irradiation

Abstract

3D nano-crystallization has been investigated with a femtosecond laser beam in 33Li2O-33Nb2O5-34SiO2 glass by changing the pulse energy and polarization direction. Electron backscattered diffraction was used to characterize the size and the orientation of crystals in cross sections of laser tracks, while second harmonic generation was employed to investigate the nonlinear optical properties of laser lines macroscopically. We are the first, to the best of our knowledge, to reveal that crystals of nano-size were precipitated both at low pulse energy with laser polarization parallel to the laser motion direction and at high pulse energy in the perpendicular case, but they preferred to orientate perpendicularly to the written lines in the former case.