<title>Laser-strength mirrors for high-power NIR-region solid state lasers</title>

Abstract

Some aspects of obtaining high reflective (HR) dielectric mirrors with high damage threshold (LDT) for high-power solid-state near IR region (NIR) lasers are considered. Optical properties of these mirrors were investigated as properties of each alternate layer evaporated with high- index (H) or low-index (L) materials as multilayer system that depends on mirror construction, parameters of evaporation, ion-beam influence, substrate materials and quality of substrate surface. Refractory oxides ZrO2,HfO2, Ta2O5, Al2O3 and SiO2 were used as starting materials for evaporation. Ion-beam influence was estimated as changing of optical absorbance at a wavelength 1.064 micrometers by laser modulated photo-thermal radiometry. Besides the quality of various work-up substrate surface was controlled by this method also. It was noticed that substrates with different surface roughness had different absorption. It was noticed that band edge of absorption of pure substrate in UV region influenced on laser damage threshold of mirrors. Optical properties of evaporated mirrors were tested as the ability of strength for laser irradiation as cavity-mirrors of high power lasers. ZrO2/SiO2 mirrors had the most high laser strength. Estimated value of laser density was 3.6 GW/cm2.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.