Optimization of the ablation process using ultrashort pulsed laser radiation in different burst modes

The authors report on a solid-state burst mode amplified laser source capable of varying the pulse duration in the range of 0.24–10 ps and generating pulse trains (bursts) with an intraburst pulse repetition rate of 65 MHz (MHz burst mode) and 2.5 GHz (GHz burst mode). Furthermore, every pulse of a burst in the MHz burst mode can be divided into another GHz burst, called BiBurst. In this study, a laser radiating at 1030 nm wavelength is used to generate ablation areas and investigate the efficiency, the surface quality, and the process stability on stainless steel with different total fluences per burst, numbers of pulses per burst, and pulse durations in the MHz, GHz, and BiBurst modes. In the investigated parameter range, the highest efficiencies were obtained in the MHz burst mode with femtosecond pulses, but in this burst regime, the burst mode induced smoothing effect is dependent of the number of scans. In contrast, the process stability and the quality in the GHz and BiBurst are granted over a wide range of parameters. Thus, the actual advantages of the GHz and BiBurst regimes in terms of a high process stability and quality could be established.