Multiscale analysis of single- and multiple-pulse laser-induced damages in HfO2/SiO2 multilayer dielectric films at 532 nm
Wenwen Liu1,2, Chaoyang Wei1,*, Kui Yi1, and Jianda Shao1
- 1Key Laboratory of Materials for High Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
- 2Graduate School of Chinese Academy of Sciences, Beijing 100039, China
Nanosecond single- and multiple-pulse laser damage studies on high-reflection (HR) coatings are performed at 532 nm. For single-pulse irradiation, the damage is attributed to the defects and the electric intensity distribution in the multilayer thin films. When the defect density in the irradiated area is high, delamination is observed. Other than the 1064 nm laser damage, the plasma scalding of the 532 nm laser damage is not pits-centered for normal incidence, and the size of the plasma scalding has no relation to the defect density and position, but increases with the laser fluence. For multiple-pulse irradiations, some damage sites show deeper precursors than those from the single-shot irradiation due to the accumulation effects. The cumulative laser-induced damages behave as pits without the presence of plasma scalding, which is unaffected by the laser fluence and shot numbers. The damage morphologies and depth information both confirm the fatigue effect of a HR coating under 532 nm laser irradiation.