Ultrashort 30 <i>fs</i> Laser Photoablation for High-Precision and Damage-Free Diamond Machining
Maksym Rybachuk, Bakhtiar Ali, I. V. Litvinyuk
Abstract
A 30 fs, 800 nm, 1 kHz femtosecond was used to photoablate diamond across radiant energy doses of 1–500 kJ/cm 2, with fluences of 10–50 J/cm 2 and pulse counts from 100 to 10,000. The objective was to maximize material removal while minimizing surface roughness ( R a ) by operating above the photoablation threshold. Results demonstrate that 30 fs laser photoablation achieves R a < 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/cm 2 (10 J/cm 2 fluence, 100 pulses), an R a of 0.09 μm was achieved, satisfying ultrahigh-precision criteria ( R a < 0.1 μm). Additionally, doses below 10 kJ/cm 2 consistently met high-precision machining requirements ( R a < 0.2 μm). Photoablation efficiency peaked below 50 kJ/cm 2, after which material removal diminished, indicating nonlinear process limitations. The sp 3 diamond phase remained intact, as confirmed by the unchanged T 2g Raman mode at 1332 cm –1, with no detectable Raman G or D modes, confirming the absence of sp 2 -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.