Influence of outmost layer on laser induced damage threshold of 1 064 nm highreflection mirrors

Electron beam evaporation method was applied to deposit three sets of 1 064 nm laser mirrors with different outmost layers: quarter-wavelength HfO2， half-wavelength SiO2 and quarterwavelength SiO2 layers, respectively. High reflectivity (more than 99.8%) has been achieved for all the stacks, and irradiated at normal incidence photothermal measurements of absorption are 3.0×10-6, 5.0×10-6 and 6.5×10－6, respectively. Corresponding laser induced damage thresholds (LIDTs) are 32.5 J/cm2, 45.2 J/cm2 and 28.4 J/cm2. The relations of electric field distribution, absorption, layer material characters and LIDT are also discussed．