Regulations of oxygen-silicon ratio and microstructure to enhance laser damage resistance of fused silica via oxygen ion implantation

Abstract

Oxygen ion implantation of fused silica surface was utilized to study the regulation of chemical composition and the evolution of microstructure to understand the enhancement mechanism of the laser damage resistance. The surface quality is improved owing to the passivation of the residual defects of fused silica surface resulted from the surface sputtering induced by the energetic ions. In the un-implanted surface, the oxygen-silicon atomic ratio is 1.9, which increases with the ion fluence. The oxygen ions during the implantation can recombine the oxygen-deficient defects, but the excessive ion fluence will lead to the increased concentrations of the structural defects, especially for POR and singlet oxygen, which is also confirmed by the transformations of the ring structures of SiO₄ tetrahedra in Raman spectra. Oxygen-implantation improve the surface quality, compensate for oxygen deficiency under ultraviolet laser irradiation, and recombine the oxygen-deficient defect, thereby decreasing the probability and growth of laser damage to fused silica. The optimized parameter of ion fluence is 1 × 10¹⁷ ions/cm². This study offers a potential technique to further enhance the resistance to laser damage and growth of fused silica surface, which is crucial for the high-flux output and stable operation of ICF facilities.