High efficiency femtosecond laser ablation of alumina ceramics under the filament induced plasma shock wave

Femtosecond laser filament enables energy transfer over long distances, which is of great value for studying long-range ablation. However, the energy coupling of filament with the plasma generated by the ablation process leads to a very complex behavior which limits the ablation efficiency. This study systematically investigated the ablation mechanism of laser-induced filament in alumina ceramic. The plasma shock wave was initially investigated using spectral detection techniques combined with Sedov-Taylor theory. The results indicated that the maximum plasma shock wave reached 30 MPa under the irradiated by a 1 mJ fs laser. The theoretical analysis confirmed the effectiveness of the filament-induced plasma shock wave in enhancing the ablation rate of alumina ceramic. In this context, the experimental studies were conducted with varying filament positions and pulse energies, and the corresponding ablation rates for each parameter were investigated. The filament in the ablation process was found to has a secondary sputtering effect, which is an effective contributor to enhance the ablation rate. The corresponding ablation depth reach to 550 μm while achieving an ablation rate of 3.1 μm³/μJ. Finally, the coupling mechanism between the femtosecond laser filament and the plasma shock wave was systematically revealed. This research will facilitate future laser remote ablation applications with high efficiency.