Effect of the pulse repetition rate on the scalability of the ultrashort pulse laser process for generating laser-induced self-organized nano- and microstructures on stainless steel

Abstract

Self-organized surface structures have gained significant interest in both science and industry. However, the scalability of the ultrashort pulse laser process for generating self-organized nano- and microstructures with varying laser pulse repetition rates has not been systematically investigated. The study investigates the transferability of laser-induced self-organized surface structures under varying pulse repetition rates (50.3 kHz to 1550 kHz) and assesses their scalability for industrially relevant processing.Our results show that low spatial frequency laser-induced periodic surface structures (LSFL-LIPSS) remain largely unaffected by variations in repetition rate at a relatively low laser fluence, highlighting their robustness and suitability for transferring small-scale laboratory experiments to large-area surface processing. In contrast, self-organized microstructures generated at a higher fluence exhibit pronounced changes in morphology, topography, and chemistry when the repetition rate exceeds 300 kHz. These changes are attributed to heat accumulation, which shifts growth mechanisms toward heat-driven processes, thereby altering surface chemistry, promoting the adsorption of organic species, and accelerating wetting transitions.Overall, these findings provide new insights into the role of repetition rate in tailoring surface functionalities and highlight pathways for scaling ultrashort pulse laser processing toward industrial applications.