Ordered mesoporous antireflective films for 1053 nm high power pulse laser

Single-layer silica films are prepared via evaporation-induced-self-assembling process using triblock copolymer surfactant F127 as template and tetraethoxysiliane as precursor under acidic condition. After ammonia pretreatment, the as-deposited films undergo a thermal decomposition process to remove the surfactant, and the mesopores are formed in film. Three techniques are used to characterize the mesoscopic structure of film, i.e., grazing-incidence X-ray diffraction, nitrogen adsorption/desorption and transmission electron microscopy. The results indicate that the film has an ordered cage-like porous structure and can be indexed as the body-centered-cubic arrangement. The optical properties of the films are investigated via ellipsometry and UV-VIS-NIR transmission spectrometer. The transmitance can reach up to 99.9% at 1053 nm wavelength. The refractive index varies with the molar ratio of F127/Si. Atomic force microscope is used to probe the surface morphology, and the surface roughness Ra is 1.2 nm. A 1053 nm laser is used to determine the laser damage threshold of film and all the thresholds are higher than 25 J· cm-2 (1 ns). This method has a potential application in the preparation of large-aperture antireflective films.