Influence of the Composition and Morphology of Dielectric Mirrors of Lidar Systems on their Optical Breakdown Threshold

The influence of the morphology and composition of thin films which form the structure of dielectric mirrors of optical cavities of coherent sources for lidars is studied. TiO2/SiO2 and ZnS/YbF3 dielectric mirrors were simulated in Optilayer software; their morphological features were determined with the use of electron and atomic force microscopy. Interference coating of the calculated structure was deposited onto a substrate by the ion-beam sputtering method. The Nd:YAG laser- (wavelength of 1064 nm) induced breakdown threshold was found to be 4 J/cm2 for a TiO2/SiO2 mirror and 3.2 J/cm2 for a ZnS/YbF3 mirror. The result can be useful for manufacturing dielectric mirrors with high optical breakdown thresholds for both sources and detectors of lidar systems.