A comparative study on MHz and GHz bursts addressing the polarization-based control of laser-induced modifications in fused silica

• Polarization-based control of volumetric cracks formed inside fused silica using burst regime is demonstrated. • GHz burst is shown to be more advantageous over MHz in modification formation via filamentation. • Volumetric modifications with longitudinal lengths up to 1.4 mm and transverse lengths of 41 μm are demonstrated. Self-filamentation of laser beams is widely used in glass scribing. However, the scribing speed is usually limited due to a small transverse damage zone of the modifications. Therefore, the processing time could be improved by forming controllable cracks. In this paper, we demonstrate a polarization-based control of cracks formed using burst regime. To the best of our knowledge, this is the first time a volumetric laser-induced crack control by polarization is reported inside fused silica . This research also includes a comparative study of MHz and GHz burst regimes on modification lengths and positions. The GHz burst is shown to be more advantageous over the MHz regime, as it allows forming more uniform modifications with longer cracks. However, both MHz and GHz bursts are eligible for controllable crack formation. At the polarization-controlled regime modification longitudinal lengths reached up to 1 mm and transverse lengths up to 32 μm. These results indicate that filamentation scribing using bursts has the potential to increase the scribing speeds up to tens of meters per second.