Laser Damage Performance Study of Fundamental Frequency Dielectric Film Optical Elements

In laser application systems, the optical film is one of the most important parts of the system, as well as its weakest link. Its damage performance determines the output characteristics and safety performance of the laser system. This paper focuses on the fundamental frequency reflection of dielectric films used in large high-powered laser devices. The study of the dielectric film's initial laser damage performance and laser damage growth performance is carried out through laser damage testing and microscopic morphology testing of the damage. The results show two different damage morphologies: type 1 damage (film discoloration damage) and type 2 damage (cratered damage), and the damage growth behavior between the two is very different, with type 1 damage not growing and type 2 damage growing rapidly under subsequent episodes that trigger their damage fluxes. The difference in the growth behavior is well explained by the micro-zone surface shape of the damage location. The results of this paper help to deepen the understanding of the dielectric membrane element processing process and the damage growth behavior.