Proton stitching of layers of SiO2 particles to fused silica

Irradiation with 100-keV protons to doses of 2.3x1015--7.6x1016 H/cm2 enhanced the adhesion and abrasion resistance of 220-nm-thick antireflective, optical coatings on fused silica substrates without adversely affecting the optical transmission and laser-damage threshold for 1064-nm photons. The as-deposited, sol-gel coatings consisted of porous layers of uniform, spherical silica particles having diameters of either 8 or 20 nm. The proton doses required for significant improvements in adhesion and abrasion resistance increased with particle diameter and decreased slightly for coatings precleaned by exposure to ultraviolet radiation in the presence of reactive gases