Advanced nanoporous SiO2 coatings for ultraviolet laser-resistant high-reflection and anti-reflection optics

Enhancing the laser resistance of coating materials represents an effective strategy. By constructing both high-refractive-index (n) and low-n layers of dielectric coatings from SiO2 materials with a large band gap and low absorption loss—specifically, dense SiO2 and porous SiO2 layers—the laser-induced damage threshold (LIDT) of the coatings can be significantly improved.

In this study, we demonstrate the fabrication of all-silica laser-resistant anti-reflection (AR) and high-reflection (HR) coatings using a combination of plasma ion-assisted electron-beam co-evaporation of an Al2O3-SiO2 mixture and a subsequent selective chemical etching process. Experiments proved the suitability of this method for producing large-scale multilayer coatings. The porous SiO2 layer exhibited absorption comparable to that of the fused silica substrate.