Effect of SiO2 barrier layer on laser induced damage threshold of second harmonic antireflection coatings on LiB3O5 crystal

Two different kinds of second harmonic antireflection(AR) coatings, with and without SiO2 barrier layer were prepared with ion assisted deposition on LiB3O5 crystal. Laser induced damage threshold(LIDT) by multiple-shot irradiation at 1 064 nm was studied and two typical damage morphologies were observed by SEM. The AR coatings with SiO2 barrier layer have an excellent LIDT, which is about 40% higher than that of coatings without barrier layer. The mechanism of LIDT enhancement by adding SiO2 barrier layer is also discussed.