Substrate Dependence of Laser-Induced Damage Threshold of Scandium Oxide High-Reflector Coatings for UV Pulsed Laser

The substrate dependence of the laser damage threshold of high-reflector (HR) coatings (Sc2O3/MgF2 HRs and Sc2O3/SiO2 HRs) for a 355-nm pulsed laser was examined. A correlation between the thermal expansion coefficient of the substrates and the damage thresholds was observed: HRs on substrates with larger thermal expansion coefficient (BK-7, sapphire) had higher threshold than those on substrates with a smaller coefficient (fused silica).