Laser micromachining of steel and copper using femtosecond laser pulses in GHz burst mode

Investigations on the ablation of steel and copper with femtosecond laser pulses using single pulses and bursts of infinite sequence of pulses with 1 GHz intraburst repetition rate are presented in this paper. The ablation efficiency is compared to the case of single femtosecond laser pulses. Based on the literature a model of the ablation process is presented explaining the behavior of a pulse burst and the good qualitative agreement of the numerical and experimental ablation efficiencies is obtained. •Laser ablation by femtosecond burst pulses is facilitated by the heat accumulation.•Bursts with a 1 ns period cause lower ablation efficiency than the single pulses.•At 1 GHz intra-burst rate, plasma shielding reduces the amount of absorbed energy.