Research on green femtosecond laser cutting mechanism for CVD diamonds

Abstract To investigate the ablation mechanism and characteristics of femtosecond laser cutting of CVD diamonds, experimental and theoretical studies were conducted. The effects of different laser parameters on kerf quality were studied. It showed that the original kerf obvious cracks and significant carbonization due to ns-laser cutting process. By adopting green fs-laser with parameters around ablation threshold, kerfs with no microscopic cracks were found with the surface roughness of 5.278 µm. SEM-FIB analysis revealed the average thickness of carbonization layer reduced to 1.206 µm compared with the initial thickness of 2.211 µm. Further experiments were conducted in the nitrogen atmosphere, where the roughness of kerfs furtherly decreased to 2.705 µm with no graphitization layer. It revealed that material removal for CVD diamonds during femtosecond laser processing was mainly occurred via sublimation. The thermal affected region could be effectively suppressed to achieve cold processing effect. XRD analysis of the kerfs indicated the precipitation of graphite phase due to thermal effects during laser process, while the introduction of femtosecond laser with protective gas could effectively suppress graphite phase formation and promote the quality of kerfs, thus achieving the clean kerfs of CVD diamonds.