Ultra-short pulsed laser ablation of highly oriented pyrolytic graphite

Abstract Highly oriented pyrolytic graphite (HOPG) targets were irradiated by use of an ultra-short pulsed (pico to femtosecond) Ti:Sapphire laser operating at 825-nm wavelength. The morphology and quality of laser ablated surfaces were characterized by stylus profilometry, scanning electron microscopy (SEM), atomic force microscopy (AFM), and Raman spectroscopy. The results were also compared with those obtained in nanosecond pulsed excimer laser ablation. The ablation rates expressed in depth per pulse were substantially higher for ultra-short pulsed lasers, and were in close agreement with the theoretical model predictions of laser–solid interactions in the short-pulse regime. Post-analysis of laser irradiated regions revealed a reduction in thermal effects and a decrease in the formation of diamond-like carbon as the pulse width was shortened. This work demonstrates the clean and precise machining capabilities of ultra-short pulsed lasers for HOPG that could be applied in the areas of thin-film deposition, nanotube synthesis, and dust-free machining.