Ultrafast lasers generally cut glass in one of two ways: Filamentation or Bessel Beam Cutting.
1. Filamentation Cutting
Laser filamentation utilizes filament phenomenon of laser and is a nonlinear effect of ultrashort pulse laser, which is the dynamic balance between Kerr self focusing and plasma defocusing.
The compression of the pulse space and time domain under the effect of self focusing leads to the sharp rise of the peak power density, which leads to the nonlinear ionization of the sample after reaching a certain threshold and produces plasma.
The generation of plasma makes the pulse disperse in space. After the defocusing effect of plasma is weakened, the scattered pulse in space will compress in space and time domain under the action of self focusing. After a certain distance, the self focusing will be terminated by plasma, thus forming a second focus. If the energy of the pulse is high enough, more focus may be formed in this way, resulting in multiple focusing.