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A 30 fs, 800 nm, 1 kHz femtosecond was used to photoablate diamond across radiant energy doses of 1–500 kJ/cm2, with fluences of 10–50 J/cm2 and pulse counts from 100 to 10,000. The objective was to maximize material removal while minimizing surface roughness (Ra) by operating above the photoablation threshold. Results demonstrate that 30 fs laser photoablation achieves Ra < 0.1 μm, meeting both high- and ultrahigh-precision machining standards, while maintaining surface integrity and preventing heat-affected zone (HAZ) damage. At 1 kJ/cm2 (10 J/cm2 fluence, 100 pulses), an Ra of 0.09 μm was achieved, satisfying ultrahigh-precision criteria (Ra < 0.1 μm). Additionally, doses below 10 kJ/cm2 consistently met high-precision machining requirements (Ra < 0.2 μm). Photoablation efficiency peaked below 50 kJ/cm2, after which material removal diminished, indicating nonlinear process limitations. The sp3 diamond phase remained intact, as confirmed by the unchanged T2g Raman mode at 1332 cm–1, with no detectable Raman G or D modes, confirming the absence of sp2-related graphitization, structural disorder, or nitrogen vacancy (NV) center annealing. These findings establish 30 fs laser processing as a high-precision, damage-free approach for diamond machining, with promising applications in NV center-containing quantum materials and advanced tooling.
Rybachuk et al. (Tue,) studied this question.