Laser-induced damage of multilayer dielectric gratings with picosecond laser pulses under vacuum and air

Abstract In this study, laser damage tests of multilayer dielectric gratings (MDGs) are performed in vacuum (5×10 −4  Pa) and in air at a wavelength of 1053 nm with pulse widths of 0.56 ps ~9.7 ps. The laser-induced damage threshold (LIDT) of MDGs in vacuum/air ranges from 2.1/2.2 J/cm 2 to 4.4/4.8 J/cm 2 for laser beams of normal incidence. The LIDT of MDGs follows a τ 0.26 scaling in the pulse width regime considered. The typical damage morphologies in the two environments caused by the near threshold pulse were observed using a scanning electron microscope (SEM); the results indicate that the damage features of MDGs in vacuum are the same as those in air. The testing results reveal that a clean vacuum environment neither changes the laser damage mechanism nor lowers the LIDT of MDGs.