Picosecond dual-pulse laser ablation of fused silica.

This study discussed the ablation thresholds of picosecond laser dual pulses in fused silica with different temporal separations. The results indicate that the lowest damage threshold of the dual-pulse ablation is at a temporal separation of 100 ps, which is only half of the threshold of the conventional pulse ablation. Furthermore, the energy ratios of two sub-pulses were optimized to minimize the thresholds. Regarding the underlying physical mechanisms, this study found that the first sub-pulses initially excited the electrons of the fused silica, and subsequently induced free-electron shielding and self-trapped exciton seed generation at different temporal separations. This either decreased or increased the material absorption of the second sub-pulses, resulting in changes of the ablation threshold of the fused silica. The results of the picosecond dual-pulse ablation could provide further understanding into the interaction mechanisms of dual pulses to transparent materials. [ABSTRACT FROM AUTHOR]