High-quality sapphire microprocessing by dual-beam laser induced plasma assisted ablation.

Sapphire is a kind of ultrahard transparent material with good chemical resistance. These great properties also make sapphire functional device fabrication a big challenge. We propose a novel dual-beam laser induced plasma assisted ablation (LIPAA) for high-quality sapphire microprocessing. One laser beam is focused on a sacrificial target for nano-particle generation by LIPAA to assist the sapphire ablation by the other laser beam. The new technology can reduce the ablation threshold of sapphire and the roughness of the fabricated structures. The laser fluence for particle generation is optimized. Furthermore, we demonstrate a sapphire Dammann grating and an OAM generator fabricated by this method. This method can be expanded to arbitrary transparent material precision machining for various applications.