Functionalization of sapphire surfaces using fs-laser radiation and selective etching

The change of surface properties, e.g. wettability and optical properties of sapphire surfaces, by direct writing of large ripple areas using a technique called “In-volume Selective Laser Etching” (ISLE) is demonstrated. In the process the sample is irradiated and by that modified/nano structured in the focal volume of the laser beam. The laser radiation is focused and scanned on the surface of the sample. Afterwards the sample is chemically wet etched using 48 % hydrofluoric acid (HF) to remove the modified material. In this paper the direct structuring of large ripple areas on transparent dielectrics up to 11 mm in diameter is shown for the first time. First achieved results will be discussed and an outlook to future applications will be given. The surface patterning is carried out with a 1.5 W FCPA laser system from IMRA.