High Power and Contamination Properties of All-Silica High Reflectivity Multilayers

Optical multilayers created from a single material have been demonstrated to have lower stress and lower thermal expansion mismatch than standard two-material coatings; however, questions of high power operation and vulnerability to environmental contamination remain. This study examines the particle-induced laser damage properties of all-silica high reflectivity multilayers, specifically those for high average power illumination. All-silica infrared reflectors were deposited by oblique angle deposition (OAD). All-silica mirrors showed low overall stress and had smaller stress changes with temperature. Their laser-induced damage thresholds (LIDTs) under high-power continuous wave (CW) laser illumination with carbon particulate contamination are significantly higher than corresponding high reflectivity multilayers composed of two materials.