Laser-induced damage of sol-gel coating

Laser-induced damage of optical thin film/silica system was studied. The thin film was sol-gel derived silica antireflective coating, which was plated on silica substrate, and the laser with 355 nm wavelength and 6.3 ns pulse width was used in measurement. The results show that the laser induced damage threshold of the system equals to that of the silica substrate and increases with the latter’s increase. The threshold of the system is 4.9 J/cm2 when the threshold of the substrate is 4.8 J/cm2. When the threshold of the substrate is increased to 7.2 J/cm2 by laser pretreatment, the system threshold increases to 7.3 J/cm2. According to dynamic comparison, the substrate is the fragile part in the film/silica system, which is damaged first under la