Femtosecond Laser Ablation of Al₂O₃ ceramics

Abstract

Laser-ablation experiments were performed on Al₂O₃ ceramics with Gaussian laser beam (800 nm wavelength, 100 fs pulse duration, 1.4 - 21 J/cm² fluence range) focused to 33 mm spot diameter (at 1/e intensity level). The ablation threshold was determined by two different methods. The first one was applied to the ablation rate dependence on the laser fluence. The second method was applied to the crater surface diameter dependence on the laser fluence. These two dependences have been well expressed by the formulas applied to metals. The ablation threshold for Al₂O₃ ceramics was found to be 1.43±0.7 J/cm². A micro-hole drilling of ceramics (150 mm-thickness) was demonstrated with laser fluence of 20 J/cm². Aspect ratio (crater depth/diameter) of 3 has been achieved.