Intense laser pulses can cause superheating of the near-surface volume of materials. This mechanism is widely used in applications such as laser micromachining, laser ablation, or laser assisted thin film deposition. The relaxation of the near solid density superheated material is not well understood, however. In this work, we investigate the relaxation dynamics of the superheated material formed in several dielectrics with widely differing physical properties. The results suggest that the relaxation process involves a number of distinct phases, which include the delayed explosive ejection of microscale particles starting after the pressure of the superheated material is reduced to about 4 GPa and for a time duration on the order of 1 μs. The appearance of a subset of collected ejected particles in fused silica is similar to that of micro-tektites and provides information about the state of the superheated material at the time of ejection. These results advance our understanding of a key aspect of the laser–material interaction pathway and can lead to optimization of associated applications ranging from material processing to laser surgery.
- Laser damage
- Laser materials processing
- Laser-induced breakdown
- Optical materials
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Electronic, Optical and Magnetic Materials