Sapphire surface patterning using femtosecond laser micromachining

This study presents an alternative method for micron-resolution patterning of a sapphire surface utilizing the characteristic of an ultra-short pulse (10^-15 s) from ytterbium (Yb) femtosecond laser (FS-laser) irradiation. Conventional processes often involve several steps, such as wet chemical or dry etching, for surface structuring of sapphire. In this study, two-dimensional array patterns on the sapphire surface with an area of 5 × 5 mm² and a depth of 1.2 ± 0.1 μm can be directly and easily fabricated by a single step of the FS-laser process, which involves 350-fs laser pulses with a wavelength of 517 nm at a repetition rate of 100 kHz. The measured ablation depths on the sapphire surface display that the proposed process can be under wellcontrolled conditions. Based on the design changes for being quickly implemented in the micromachining process, a FS laser can be a promising and competitive tool for patterning sapphire with an acceptable quality for industrial usage.