The characteristic parameters of initiating defects in HfO₂/SiO₂ high-reflector multilayer thin film at wavelength of 1064 nm^*

¹ School of Science, Beijing Technology and Business University, Beijing 100048, P.R. China
² Key Laboratory of High Power Laser Materials, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, P.R. China

^a e-mail: lixiaoustc@163.com

Received: 26 February 2014
Revised: 28 June 2014
Accepted: 15 July 2014
Published online: 13 August 2014

Abstract

The characteristic parameters of initiating defects in HfO₂/SiO₂ high-reflector film at wavelength of 1064 nm are investigated through the combined application of laser-conditioning process and the multispot damage threshold test. The laser damage tests before and after laser-conditioning are carried out within three different spot diameters. The damage threshold and the density are considered to characterize the initiating defects which are shown to be susceptible to laser damage. These characteristic parameters are obtained through fitting the damage data with the spot size effect. The influence of laser-conditioning effect on the initiating defects is analyzed. The initiating defects are specified by a Gaussian distribution after laser-conditioning. It is discussed the essential roles of the initiating defects to the damage threshold of the film. The investigation on characteristic parameters of initiating defects has potential to be applied in the mechanisms of laser induced damage and laser-conditioning, as well as in the direction the preparation of the films.