Polarization-dependent microstructural evolution induced by a femtosecond laser in an aluminosilicate glass

Manipulation of femtosecond laser induced microstructures in glass by tuning the laser polarization has great potential in optics. Here we report two different polarization-dependent microstructures and their evolution with pulse repetition rate in an aluminosilicate glass induced by femtosecond laser irradiation. A V-shaped crack oriented parallel to the laser polarization plane is induced at the bottom of modified regions by pulses operated at 200 kHz, 1030 nm, and 300 fs. Further increasing the pulse repetition rate to 500 kHz leads to the formation of a dumbbell-shaped structure, which is elongated perpendicularly to the laser polarization, at the top of the modified region. The size of the coloration area and the dumbbell-shaped structure can be controlled by tuning the pulse duration. Further investigation indicates that higher numerical apertures are in favor of the presence of the polarization effects in femtosecond laser irradiation. The possible mechanism responsible for the formation of the two microstructures is discussed. These results could be helpful for understanding of ultrafast laser interaction with glass.