Spatiotemporally Shaped GHz-Burst Femtosecond Bessel Beams for Precision Microgrooving of Cf/SiC Composites

Precision machining of Carbon fiber-reinforced silicon carbide (Cf/SiC) composites remains challenging because their heterogeneous architecture leads to nonuniform laser–material interactions and poor dimensional control during material removal. In this work, GHz-burst femtosecond Bessel beams were employed for microgrooving of Cf/SiC composites and compared with Gaussian beams under the same burst mode. The study focused on how beam spatial distribution, laser parameters, and fiber orientation influence groove formation and material-removal behavior. Near the removal threshold, the Bessel beam produced a groove narrower than 3 μm, compared with approximately 40 μm for the Gaussian beam, demonstrating its capability for micron-scale precision structuring. At higher powers, the Bessel beam retained strong axial removal, producing a groove width of 220 μm compared with 312.82 μm for the Gaussian beam, while increasing the groove depth by 92.8%. Apparent equivalent removal-threshold analysis further revealed distinct responses of the two optical fields. Bessel-beam processing evolved from central-lobe-dominated removal near the threshold to combined central-lobe–side-lobe removal as power increased, whereas Gaussian-beam processing showed a more continuous lateral expansion. Morphology, element characterization and in situ high-speed imaging further showed enhanced interaction with the SiC matrix, transport and redeposition of Si-O containing species, and a more axially concentrated plume during high power Bessel-beam processing. These findings clarify the role of spatial energy distribution in GHz-burst femtosecond processing of heterogeneous Cf/SiC composites and provide a processing route from micron-scale precision microstructuring to efficient deep-groove machining and cutting.