Influence of surface damage on the optical properties of sapphire and its etching repair method

Sapphire optical components are prone to cracks and scratches during grinding, installation, and service, which affects the laser damage resistance. In order to improve the laser damage resistance of sapphire damaged surface, the influence of surface damage on the laser damage resistance was analyzed. The repair mechanism of wet etching on the damaged surface was expounded. The results show that the reduction of damage frequency and depth can reduce the LIMF, and the LIMF caused by ellipsoidal damage is less than prism damage. The texture direction relationship between the two surfaces influences the internal LIMF. Compared with the vertical surface damage, the parallel surface damage has a larger LIMF value. The LIMF value of the etching surface is minimal. The characteristics of the damaged surface before and after etching were compared. The results show that the surface damages are passivated and merged after etching, and the surface transforms into ellipsoidal features. These changes are conducive to improving the laser damage resistance. Finally, the effect of the etching process on surface quality is analyzed. The formation mechanism and etching repair mechanism of sapphire damaged surface at the atomic scale were revealed by molecular dynamics simulation. Finally, the laser damage resistance of sapphire surface was tested, and the feasibility of wet etching was verified.