Influence of SiO_2 undercoat on the laser-induced damage threshold of 355 nm LaF_3/AlF_3 multilayer reflectors

摘要

In the pursuit for 355 nm high laser resistant dielectric coatings, layer-pair number of 10 and 15 LaF_3/AlF_3 high reflectors with and without SiO2 undercoat were prepared on BK7 substrates. The results indicate considerable increase in 355 nm laser-induced damage threshold (LIDT) for samples with undercoat. The samples were analyzed in Normalized Electric Field Intensity distribution, total stress, damage depth and damage morphology, revealing that SiO_2 undercoat benefits fluoride coatings by shielding substrate defects and reducing coating defects.