title: Contamination-resistant silica antireflective coating with closed ordered mesopores.
abstract: Porous silica optical antireflective (AR) coatings prepared by traditional sol-gel method have been extensively used for high power laser systems, but a serious drawback is that contamination existing in the high vacuum is easily absorbed by the disordered open pore structure, resulting in a fast decrease in transmittance. To improve the stability of transmittance in vacuum, a contamination-resistant silica AR coating with ordered mesopores completely closed by hydrophobic-oleophobic groups was successfully developed on a fused quartz substrate. The ordered mesopores in the coating were controlled under the direction of surfactant F127 via an evaporation-induced-self-assembling process and then were closed by post-grafting long chain fluoroalkylsilane. The grazing incidence small angle X-ray scattering (GISAXS) and the X-ray reflectivity (XRR) results indicated that the mesopores in the coating constructed a Fmmm orthorhombic symmetry structure with a (010) plane parallel to the substrate. Cage-like mesopores were confirmed by nitrogen adsorption-desorption analysis. The obtained coatings showed low surface roughness, excellent abrase-resistance and high transmittance of 100% on quartz substrate. Especially, the decrease of transmittance tested with polydimethylsiloxane pollution in vacuum within one-month was as small as 0.02%. The laser induced damage threshold was up to 59.8 J cm(-2) at a 12 ns laser pulse of 1053 nm wavelength. This work provides an alternative way to fabricate AR coatings with high stability.
authors.affiliation: Key Laboratory of Carbon Materials, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, China. xuyao@sxicc.ac.cn.
authors.forename: Jinghua
authors.initials: J
authors.lastname: Sun
authors.forename: Qinghua
authors.initials: Q
authors.lastname: Zhang
authors.forename: Ruimin
authors.initials: R
authors.lastname: Ding
authors.forename: Haibing
authors.initials: H
authors.lastname: Lv
authors.forename: Hongwei
authors.initials: H
authors.lastname: Yan
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Yuan
authors.forename: Yao
authors.initials: Y
authors.lastname: Xu