Surface-texturing of sapphire by femtosecond laser pulses for photonic applications

We demonstrate that F+ centres (oxygen vacancy with a trapped electron) are induced by femtosecond laser scribing of a crystalline Al2O3 wafer and that they can be fully annealed at 1100 degrees C. The corresponding photoluminescence band at 325 nm which is induced by the femto second laser structuring of a sapphire surface is extinct after heat treatment. Thermal activation of oxygen diffusion in sapphire can explain the observation. The potential of pre-textured sapphire in lighting and micro-optical applications is discussed.