Study on Laser Conditioning Parameters of HfO<sub>2</sub>/SiO<sub>2</sub> Mul tilayer Mirrors

Abstract

Laser conditioning is an effective method to improve the laser damage threshold of HfO 2 /SiO 2 multilayer films prepared by electron beam evaporation. In this paper, some parameters that can affect the efficiency of laser conditioning were discussed. The result is that the maximum conditioning fluence should be less than 90% of its unconditioned laser induced damage threshold (LIDT) to avoid damage to the film. The laser beam increment between pulses and laser conditioning steps has a great influence on the improvement of damage threshold of HfO 2 /SiO 2 multilayer high reflective coatings. The coverage of the light intensity on the defect should be as wide as possible, and the irradiation of light intensity should be as high as possible. The main mechanisms of laser conditioning of HfO 2 /SiO 2 multilayer high reflective coatings may be the removal of Hf, Si and O ions and the removal of the defects in the films.

Laser-induced damage threshold in HfO2/SiO2) multilayer films irradiated byβ-ray

“…Multilayer optical films fabricated from hafnium dioxide (HfO 2 ) and silicon dioxide (SiO 2 ) with high laser induced damage threshold (LIDT) are important components in high power laser systems. [1][2][3][4] A key use for these films is to improve the damage resistance of high power lasers. Postprocessing can effectively improve the resistance to laser damage.…”

“…Postprocessing can effectively improve the resistance to laser damage. In general, the post-processing methods of optical films include surface processing, [3,5,6] heat treatment, [7][8][9] post hot isostatic pressing, [9,10] etc. Among these methods, surface processing can increase LIDT through improving surface quality.…”