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

Laser-resistant coatings are becoming increasingly essential to meet the growing demand for high-power lasers. 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. Both AR and HR coatings showed outstanding laser resistance at 355 nm. Notably, the LIDT of the AR coating (~46.9 J/cm2) surpassed that of the fused silica substrate (~41.1 J/cm2). The proposed method is simple and cost-effective, holding great promise for advancing the development of high-performance laser coating.