Investigation of the characteristics of dielectric UV mirror coatings on fatigue laser-induced damage in the single ps pulse regime

Fatigue, also known as optical component aging, is the gradual reduction in LIDT caused by a high number of laser pulses that are not powerful enough to cause initial laser damage. The duration of the laser pulse, as well as its wavelength, affects the resistance of the coating to laser-induced damage, especially at shorter pulse durations and lower wavelengths. This study’s aim was to evaluate dielectric IBS, IAD, and EB-coated UV mirrors operating in the single ps pulse regime and to define the key features that contribute to the aging of the component. For this purpose, laser-induced fatigue damage testing was completed at 343 nm wavelength using the S-on-1 procedure with single ps pulse duration by a laser system operating at a repetition rate of 200 kHz, with up to 10 million pulses per single site. LIDT values for two distinctive damage types were defined based on the observed changes in the sample: catastrophic failure and color-change modes. Subsequently, coatings with different spectral characteristics, surface properties and structural features were evaluated and their laser-induced fatigue damage results were compared.