Study On The Ultraviolet High Reflect Films With High Laser Damage Threshold

This work focused on analysis and studying of the new high LIDT ultraviolet metal/dielectric multiplayer films that was applied in power laser field. The metal/dielectric multiplayer films'optic character and laser induce damage threshold were studied by theory calculation and experiments. Firstly, The program of films temperature field was coded, it analysised the K₉/Al(HfO₂/SiO₂)^6/air,K₉/(HfO₂/SiO₂)^3Al(HfO₂/SiO₂)^3/air,K₉/Al(ZrO₂/SiO₂)^6/air,K₉/(ZrO₂/SiO₂)^3Al(ZrO₂/SiO₂)^3/air multiplayer films temperature field changes in different time after laser irradiated. The result indicated that the K₉/Al(HfO₂/SiO₂)^6/air K₉/Al(ZrO₂/SiO₂)^6/air,K₉/(ZrO₂/SiO₂)^3Al(ZrO₂/SiO₂)^3/air multiplayer films may be applied in power laser field. Secondly, The K₉/Al(HfO₂/SiO₂)^6/air multiplayer films were deposited by electric beam evaporation. The films were compact, uniformity and the two layers'interface was smooth. The substrate's RMS was improved after deposited metal HR films. The lower RMS films have higher reflective index and its wavelength was excursed toward infrared. After absorbing water, the films spectrum was excursed toward short wavelength. Measured by spectrophotometer in litter angle, the films spectrum was excursed toward long wavelength and the reflective was reduced. Measured by spectrophotometer in big angle and compared with zero degree angle measured, the spectrum was excursed toward short wavelength and the reflective was raised. In the same substrate thickness, metal/dielectric multiplayer films stress was accrete when the films thickness accreted, and was changed from compass stress to tensile stress. From the analysis of laser induce damage the cause, we know the causes of power-laser irradiated induce damage may be absorption, laser interference, nodule seek and stress etc. The last, The ZrO₂ films were deposited by electric beam evaporation. We found that: in the same substrate and different deposited temperature, the films refractive index and extinct index were improved by raised the substrate temperature. The films laser induce damage threshold were reduced when the substrate temperature rose. In the same temperature and different substrate, the solid silica substrate films'refractive index and laser induce damage threshold were higher than the K9 substrate films'. On the contrary, the solid silica substrate films'extinct index are lower than the K₉ substrate films'. After absorbing water, the films transmission was reduced, while the films refractive index and extinct index were excursed toward long wavelength.