Post-treatment of 351 nm SiO2 antireflective coatings for high power laser systems prepared by the sol-gel method

Abstract

Different post-treatment processes involving the use of ammonia and hexamethyldisilazane (HMDS) were explored for application to 351 nm third harmonic generation SiO 2 antireflective (3 SiO 2 AR) coatings for high power laser systems prepared by the sol-gel method. According to experimental analysis, the 3 SiO 2 AR coatings that were successively post-treated with ammonia and HMDS at 150C for 48 h and again heat-treated at 180C for 2 h (N/H 150 + 180 AR) were relatively better. There were relatively fewer changes in the optical properties of the N/H 150 + 180 AR coating under a humid and polluted environment, and the increase in defect density was slow in high humidity environments. The laser-induced damage threshold of the N/H 150 + 180 AR coating reached 15.83 J=cm 2 (355 nm, 6.8 ns), a value that meets the basic requirements of high power laser systems.