Post-treatment of 351 nm SiO_(2) antireflective coatings for high power laser systems prepared by the sol-gel method

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(3ω SiO_(2)AR) coatings for high power laser systems prepared by the sol-gel method.According to experimental analysis,the 3ω SiO_(2)AR coatings that were successively post-treated with ammonia and HMDS at 150℃ for 48 h and again heat-treated at 180℃ 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;(355 nm,6.8 ns),a value that meets the basic requirements of high power laser systems.