Investigating burst mode ultrashort pulse laser ablation on stainless steel: a combined numerical and experimental study leading to an analytical model

Femtosecond lasers have proven to be a highly effective tool for surface micro- and nanomachining, offering high precision through minimal heat-affected zones compared to longer-pulse lasers. Moreover, recent advancements in burst technology show great promise for enhancing both efficiency and precision. This study investigates the dependence of fluence and sub-pulses on the ablation depth and diameter of 316L Stainless Steel with a MHz intraburst repetition rate is investigated. An extended two-temperature model, incorporating the heat diffusion between sub-pulses, is introduced to predict ablation depth and diameter for varying number of sub-pulses. Simulated results are compared with experimental data, showing a good qualitative agreement between them. The findings reveal that burst mode can significantly improve ablation rates by mitigating efficiency loses at high fluence and provide insights into how to achieve the optimal parameters for its application.