Laser damage growth characteristics of HfO₂/SiO₂high reflection film at 1064 nm

The high reflection films will be damaged when irradiated by high power laser. With the increasing of the laser energy and the numbers of irradiation, the sizes of the initial damaged structure will grow, which has a serious effect on the application of the optics. In this paper, the varying rules, the damage feature and the damage growth threshold of the HfO2/SiO2 high reflection films under 1064 nm laser irradiation have been investigated. The results indicate that the lateral dimension of the delamination initial damage structure increases almost multi-linearly with the rise of laser fluence. The damaged growth threshold along the vertical expanding is more than twice as it along the horizontal expanding. In addition, the growth rate of the initial damaged structure grows with the rise of the laser fluence exponentially in the horizontal direction while the damage growth threshold decreases obviously with the rise of the shots.