Femtosecond laser technology has opened a large variety of industrial applications. The short duration of the laser pulses enables material minimal collateral damages due to thermal effects, which makes possible to reach a high precision in micro-processiing. This is sometimes at the expense of industrial productivity, since a single femtosecond pulse will only remove a limited amount of matter. Increasing process throughput productivity can be achieved by increasing the  repetition rate of the laser, but he onset of thermal accumulation in the material limits this approach.

Femtosecond pulses with bursts of GHz repetition rate can significantly improve the ablation efficiency of femtosecond lasers. Freely adjustable bursts involve thermal and non-thermal ablation mechanisms. The long GHz bursts can remove very efficiently heated matter, with non-thermal ablation leading to a high-quality material processing. We report an experimental study on crystalline silicon line scribing with GHz burst regime of femtosecond pulses at 515 nm. The number of pulses per bursts varied from 50 ppb to 200 ppb. A second harmonic generation module was placed at the output of a 100 W femtosecond GHz laser to generate up to 50W of second harmonic (SHG,515nm) at 200 kHz. The results show the highest ablation efficiency obtained on silicon with fs pulses (more than 10 mm³/min/W), and the crucial role of the pulse overlap.