Polyvinylpyrrolidone/ZrO₂-based sol–gel films applied in highly reflective mirrors for inertial confinement fusion

Polyvinylpyrrolidone (PVP)/ZrO₂-based hybrid thin films, with suitable properties for application in the high power lasers, have been prepared combining the advantages of both the sol–gel route and the organic-inorganic hybrid materials. By virtue of light scattering analysis, the chemical composition of the reaction system was fully optimized, endowing the films with good optical properties and high laser-induced damage threshold (LIDT). Light scattering studies also provided valuable structural information about the hybrid sols, which offered a better understanding of the structure and performance of the hybrid films. Our experiments showed that, in the hybrid sols, the incomplete substitution for the chelating ligands by the hydroxyls might considerably conceal and weaken the effect of PVP on the nucleation and growth of ZrO₂ particles. Thus, the incorporation of PVP only resulted in slight decreases in the refractive index and LIDT of the films. By energy relaxation through their flexible polymer chains, however, the addition of PVP could easily enhance the stress compatibility between the high- and low-index layers and then facilitate the deposition of the multi-layer highly reflective mirrors.