Mechanisms of ultrafast GHz burst fs laser ablation

Gigahertz (GHz) femtosecond (fs) lasers have opened possibilities for enhancing and controlling the laser ma-chining quality to engineer the physicochemical properties of materials. However, fundamental understanding of laser-material interactions by GHz fs laser has remained unsolved due to the complexity of associated abla-tion dynamics. Here, we study the ablation dynamics of copper (Cu) by GHz fs bursts using in situ multimodal diagnostics, time-resolved scattering imaging, emission imaging, and emission spectroscopy. A combination of probing techniques reveals that GHz fs bursts rapidly remove molten Cu from the irradiated spot due to the recoil pressure exerted by following fs pulses. Material ejection essentially stops right after the burst irradiation due to the limited amount of remnant matter, combined with the suppressed heat conduction into the target material. Our work provides insights into the complex ablation mechanisms incurred by GHz fs bursts, which are critical in selecting optimal laser conditions in cross-cutting processing, micro/nano-fabrication, and spectro-scopy applications.

Automated summary

GHz fs bursts of laser enable the selection of optimal laser conditions for cross-cutting processing, micro/nano-fabrication, and spectroscopy applications by rapidly removing molten copper and limiting heat conduction.