Study On The Properties Of Optical Films Irradiated By High Energy Lasers

Nowadays, with the development of the laser technology, the output of laser system will be higher and higher. The optical thin film parts which play an important role in the laser systems will make complex and diverse changes by a strong electromagnetic field of thin-film laser system, the performance of these changes will change the film, and the function of the laser system will be affected. For the purpose of making the forecast, intervention and regulation in the behavior of films under the laser irradiation, it must be admitted that the changing studying of films and the changing discipline of LIDT irradiated by the laser are necessary to considered.In this paper, firstly, in order to investigate effects for the films’optical properties, microstructure and LIDT by the laser irradiation, which includes the laser energy and the laser pulse. TiO2and SiO2films irradiated by different laser energy which laser density is less than the LIDT of films are prepared on K9substrates by thermal evaporation techniques. Then, combination of materials will be carried out to prepare the high-reflection coating. The final results show that:1. For TiO2films, the refractive index is increased and the extinction coefficient has no significant changes, which makes the transmittance is reduced, besides, the thickness of films is reduced by the laser irradiation. For SiO2films, the thickness of films is reduced. In addition, the laser irradiation can improve the microstructure of the two films, and the laser damage-resistance ability of the films can be enhanced. When the laser energy is60%of the film’s LIDT, the maximum LIDT of films is obtained. 2. For high-reflective coatings which designed with the model of G|(HL)8H2L|A, the surface morphology is improved after the irradiation and the most significant improvement can be obtained when the energy density of the laser irradiation is60%LIDT. What’s more, laser energy density of40%LIDT and60%can promote the laser-induced damage threshold of films. When the irradiation energy is60%of the film’s LIDT, the maximum LIDT of films is obtained, which improved17%. Finally, LIDT of films is decreased with the increasing pulse number of the laser irradiation.