Investigations on SiO2/HfO2 mixtures for nanosecond and femtosecond pulses

After several investigations in laser induced damage behavior of oxide mixtures of different compositions, also HfO2 could be steplessly mixed with SiO2. A study of SiO2/HfO2 IBS single layers and high reflectors is presented. Damage testing has been performed at 800nm and 355nm on an extensive set of single layers employing different mixture ratios of silica and hafnia. The analysis of the response of optical single layer coatings to femtosecond and nanosecond pulse exposure provides input for further coating designs, in particular for the optimization in respect to the damage threshold properties. A deeper understanding of the damage mechanisms is gained by comparing the ns and fs pulse results as a function of the mixing ratio.