Ultrafast Ablation of Transparent Materials by Heating Excited Electrons

Microprocessing of transparent materials, such as glass, diamond and sapphire have been needed across various fields from industry to science. Among various methods for processing transparent materials, femtosecond laser processing has garnered significant attention due to its ability to enable fine machining [1]. However, it faces challenges, including crack formation during processing and an extremely slow processing speed [2]. To address these issues, we previously reported a transient and selective laser (TSL) processing [3]. In TSL processing, electrons are locally excited using an ultrashort laser pulse (Fig. 1(a)), and then, the excited region is selectively heated and ablated by a successive microsecond laser pulse (Fig. 1(b)). This significantly improved processing speed, while enabling crack-free precision machining by suppressing shock wave generations. However, the processing mechanism, dynamics, and applicability to other materials remain unclear.