Wide spectrum antireflective coating for laser fusion systems

A method to deposit a laser damage resistant, wide spectrum antireflective coating on fused silica was developed. The coating is applied from a specific silanol polymer solution and converted to a porous SiO2 film. The pore size of the film is reduced by a heat treatment to prevent UV scattering; gradation of the pore volume is achieved by a mild etching to a sufficient depth to prevent a smoother index transition from air to the substrate glass. The resulting antireflectivity covers the entire transmission range of silica and may be extended to a wavelength as short as 250 nm. Laser damage thresholds as high as 9 j/cm(2) are demonstrated on processed samples.