Femtosecond lasers are recognized for their precision and high-quality performance in the material micromachining field, experiencing increased integration into various industrial applications. Their ultra-short pulse duration nature enables precise and high-quality material processing, particularly beneficial for materials where conventional machining methods are lacking. Alumina ceramics, known for their excellent electrical insulation, corrosion resistance, wear resistance, and hardness, stand out as one of the materials significantly benefiting from femtosecond laser machining. However, the efficiency of these lasers in industrial applications has room for improvement. One way to cope with this is burst mode, featuring closely packed femtosecond pulses at MHz/GHz intra-burst repetition rates. This regime allows the division of the energy from a high-energy single-pulse into multiple smaller pulses, effectively making use of the full potential of the laser source.





This study employed the FemtoLux 30 laser to machine alumina ceramics, focusing on the impact of MHz and GHz burst mode on ablation efficiency. Our findings reveal that utilizing MHz/GHz burst mode reduces the ablation threshold (minimum fluence required to cause catastrophic damage), proportional to the increase in pulse number of the burst. Furthermore, the experiment involved milling of squares into the alumina substrate to investigate the ablation efficiency (removed volume per energy unit). As a result, machining in GHz burst mode achieved an ablation efficiency 50 times greater than that of the single-pulse regime. These results highlight the benefits of employing MHz/GHz burst mode for femtosecond laser machining of alumina ceramics, suggesting its further integration into industrial applications.