1064 nm and 350 nm laser damage thresholds of index oxide films deposited from organic solutions and sols

High index optical coatings of the oxides TiO2, Ta2O5, ZrO2 and HfO2 have been prepared from solutions of metal organic precursors and from colloidal oxide suspensions. Room temperature processing gives porous coatings of comparatively low refractive index (1.8-1.9). Heat treatments can, in some cases, increase the index. Laser damage threshold levels at 1064 nm with a single 1 ns pulse are in the range 6-10 J/cm2, which is comparable with coatings of the same materials produced by electron beam evaporation. Lower figures are obtained at 350 nm with a 25 ns pulse under multishot (25 Hz) conditions