Laser-induced damage studies in the nanosecond regime on large-aperture anti-reflection coated ceramic Yb:YAG

We report on laser-induced damage behaviour in the nanosecond regime of anti-reflection coated, large aperture, ceramic Yb:YAG. Experiments were carried out to identify suitable coatings for use in large-aperture DiPOLE cryogenic laser amplifiers and involved the testing of 9 coating types from 7 different coating suppliers. Comparison between ex-situ S-on-1 and raster scan test results confirmed that, in the case of large aperture optics, the raster scan protocol provides a more accurate estimate of failure levels compared to the S-on-1 protocol. Significant variability in performance under raster scan testing was observed for different coating types, with some coatings failing under irradiation at 5 J/cm² fluence while others surviving irradiation at 15 J/cm². Comparison between raster scan results and operational experience in DiPOLE amplifiers indicates that raster-scan testing results can be used as a good indicator for suitability in operational use.