Material Processing at GHz Burst Mode by Femtosecond Laser Ablation

Ablation of copper targets using a GHz burst mode with femtosecond laser pulses is investigated. To this end, the GHz burst mode oscillating groups of pulse train with an extremely short interval of 205 ps between each intra-pulse is generated. The pulse numbers larger than 10 in the burst significantly reduce the ablation efficiency due to the plasma shielding. The 10-pulse burst mode achieves 25 mW of the ablation threshold, which is four times smaller than 100 mW for the conventional single-pulse train femtosecond laser ablation. The GHz burst can perform precise ablation with smoother ablated surfaces.