Laser-induced damage of black glass before and after surface treatment by containing impurities-SiO₂ film during ultra clean manufacturing

Ultra-clean manufacturing is an indispensable key technology for inertial confinement fusion (ICF) to generate clean and sustainable energy, but the pollutants from laser-induced damage are a threat to ultra-clean manufacturing. Here we investigate the damage of black glass in a high laser fluence system, which refers to high fluence laser beams in fusion class laser systems. Results show a significant dependence of damage parameters on the laser pulse duration at 355 nm before and after surface treatment by SiO₂ films, which include the laser-induced damage threshold (LIDT), morphology and depth. The simulation indicates that the LIDT of SiO₂ films on black glass is improved obviously, which is 14.1 J/cm², while that of normal black glass is 10.2 J/cm². The presence of impurities will aggravate the damage of the thin films and pollutes the laser system. LIDT of SiO₂ films containing impurities is only 3.6 J/cm². The experiments show that the average LIDT of black glass is 9.54 J/cm² while that of thin films with impurities is no more than 4.12 J/cm². These salient results provide a new concept for the protection of absorbing stray light for ultra-clean manufacturing.