Sol–gel broadband anti-reflective single-layer silica films with high laser damage threshold

A simple processing of preparing broadband anti-reflective single-layer silica films is presented in this article. By adding polyvinylpyrrolidone (PVP) into reactant mixture, PVP-containing SiO2 sol was obtained under base catalyzed hydrolysis and condensation of tetraethoxysilane. The spin-coating films and the dip-coating films were deposited on one side and two sides of quartz substrates. The anti-reflection band is 315 nm wide for dip-coating film and 559 nm wide for spin-coating film and the transmittance reached to 99.95 and 95.92% for dip-coating film and spin-coating film, respectively. By a Nd:YAG lasers the laser damage threshold of as-deposited films was measured at 1064 nm wavelength (1 ns pulse). It ranged from 24 to 33 J/cm2 with an average of 28.7 J/cm2. Compared to SiO2 sol without PVP, not only was the anti-reflection band broadened but the anti-reflection and laser damage threshold were retained.