Effect of target on micromachining of sapphire using laser-induced plasma-assisted ablation

Laser-induced plasma-assisted ablation (LIPAA) has been demonstrated to be an advance micromachining technique which has a great application in the fabrication of microstructures on the transparent hard brittle materials. The sacrificial target material has a significant impact on the processing efficiency and quality of LIPAA. Here, the influence of surface roughness and types of sacrificial target materials on the micromachining of sapphire using LIPAA method was studied. The experimental results showed that the etching efficiency of LIPAA grows with increasing surface roughness of target, and eventually flattens out as the target surface roughness reaches about 1 μm. It was found that the Fe target has the highest etching efficiency, while the Si target has the best etching morphology, which is related to the absorptivity and relative atomic mass of the target. In addition, the material removal mechanism of LIPAA process was analyzed. It is concluded that the material removal of LIPAA process is a joint action of plasma etching and laser defocus ablation, and the material removal rate of plasma etching is 72% higher than that of laser defocus ablation.