Ablation characteristics of aluminum oxide and nitride ceramics during femtosecond laser micromachining

Femtosecond laser ablation of aluminum oxide (Al2O3) and aluminum nitride (AlN) ceramics was performed under normal atmospheric conditions (λ = 785 nm, τp = 185 fs, repetition rate = 1 kHz), and threshold laser fluencies for single- and multi-pulse ablation were determined. The ablation characteristics of the two ceramics showed similar trends except for surface morphologies, which revealed virtually no melting in Al2O3 but clear evidence of melting for AlN. Based on subsequent X-ray photoelectron spectroscopy (XPS) analyses, the chemistry of these ceramics appeared to remain the same before and after femtosecond laser ablation.