Damage threshold improvement of HfO2/SiO2 coating by 1 064nm laser conditioning

In this paper, the Nd:YAG laser with wavelength 1 064nm is used to study the improvement effect of damage threshold of HfO2/SiO2 coating samples. The experiment of laser conditioning effect was taken by use of N-on-1 mode, namely the irradiation energy density started from about 70% of the damage threshold, and increased 5J/cm2 energy pulse by pulse until serious damage appeared. The experiment results show that 1064nm laser irradiation can improve the damage threshold of HfO2/SiO2 coating up to 3 times. The mechanisms of laser conditioning on HfO2/SiO2 mirror are found in two forms: laser annealing and laser cleaning of coating. Laser annealing can increase the damage threshold of non-defective coating up to 3 times on the average. Laser cleaning means that coating defects such as nodul