Design and realization of antireflection coatings for the visible and the infrared based on mesoporous SiO and SiO-TiO hybrid materials.

Five-layer antireflective coating for the visible and the infrared has been successfully fabricated by a solgel route on quartz substrate. The quarter-half-quarter multilayer structure with two buffer layers is optimized by the optical admittance approach. Mesoporous SiO film templated by an ethylene oxide-propylene oxide-ethylene oxide triblock copolymer is used as the top layer, and SiO-TiO hybrid films are employed as the other layers. The grazing incidence small-angle x-ray scattering results indicate the ordered mesopores in the low-index SiO film, as well as the homogeneity of the SiO-TiO hybrid films. Transmittance spectra are fitted to obtain film thicknesses and refractive indices, providing the main technological parameters for theory designs. A short heat-treatment step followed by a shock cooling process is introduced to suppress crack formation in film stacks. The transmittance of the obtained five-layer antireflective coating exceeds 99% at 500-700 nm, and the maximum value in the infrared region is 97.84% at 1100 nm. This work is a beneficial attempt to fabricate antireflective coatings with multilayer structure through the soft solgel route.