Temperature field analysis of high reflection film induced by long-pulse and short-pulse lasers under different irradiation angles

Abstract

Modeling laser beam as a tapered wave with a Gaussian spectrum, The temperature fields in HfO2/SiO2 high-reflection (HR) film, induced by 1ms long-pulse and 10ns short-pulse lasers, under different incident angles are calculated. The damage differences between long-pulse and short-pulse-induced damage in the HR film are analyzed. The results show for long-pulse laser, the temperature distribution is much less affected by the laser field effect than short-pulse case. Furthermore, as the irradiation angles increase from 0 to 35° for 1ms and 10ns lasers, the peak temperature rises in the HR film increase for s polarized laser. Other than long-pulse laser, for short-pulse laser, the positions of the peak temperature shift gradually toward the air–film interface as the incident angle increases, which may have a great influence on the position of thermal stress coupling and damage probability.