Investigation of multi-timescale processing phenomena in femtosecond laser drilling of zirconia ceramics

Abstract

Femtosecond lasers have been applied to machining of zirconia (ZrO2) ceramics because of their ultrashort pulse duration and high peak power. However, an unclear understanding of the ultrafast laser–material interaction mechanisms limits the achievement of precision processing. In this study, a pump-probe imaging method comprising a focusing probe beam integrated with a high-speed camera was developed to directly observe and quantitatively evaluate the multi-timescale transient processing phenomena, including electron excitation, shockwave propagation, plasma evolution, and hole formation, occurring on the picosecond to second timescales, inside a ZrO2 sample. The variation mechanism in the shapes, lifetimes, and dimensions of these phenomena and their impacts on the drilling performance under different laser parameters were explored. The clear imaging and investigation of the above phenomena contribute to revealing the ultrafast laser–material interaction mechanisms and precision processing in the laser-drilling of zirconia ceramics.