Laser conditioning of high-reflective and anti-reflective coatings at 1064 nm

Abstract

Laser conditioning effects of the HfO₂/SiO₂ High-reflective (HR) and Anti-reflective (AR) coatings at 1064 nm and the accumulation effects of multi-shot laser radiation were investigated. The HfO₂/SiO₂ HR and AR coatings were prepared by E-beam evaporation (EBE). The single-shot and multi-shot laser induced damage threshold was detected following ISO standard 11254-1.2, and the laser conditioning was conducted by three-step raster scanning method. It was found that laser damage resistance of the HR coatings for both single-shot and multi-shot laser radiation was enhanced after laser conditioning, and the single-shot laser induced damage threshold (LIDT) got the greatest enhancement. There was obvious shot to shot laser damage accumulations for HR samples and the LIDT decreased as the shot number increased. Laser conditioning can also improve the multi-shot laser damage accumulations behaviors of the HR samples. However, the AR coatings had no laser conditioning enhancement and multi-shot laser damage accumulation effects. A Nomarski microscope was employed to map the damage morphology, and it found that the damage behavior was defect-initiated for both samples.