Antireflective coatings with adjustable transmittance and high laser-induced damage threshold prepared by deposition of magnesium fluoride nanoparticles

Antireflective coatings with adjustable transmittance and high laser-induced damage threshold (LIDT) have been prepared by the deposition of magnesium fluoride (MgF2) nanoparticles on fused silica substrates. The peak transmittance of the coatings is 99.98%, mainly due to the low refractive index caused by the introduction of porosity between MgF2 nanoparticles. With varying the coating thickness, the optimized antireflective performance of the coatings at any wavelength between 300 and 1100 nm can be achieved. The effect of the particle size on the antireflective properties of the coatings has been also investigated. The coatings prepared from small particles exhibit higher transmittance at short wavelengths than do the coatings prepared from large particles. The LIDTs of the coatings at 351 nm, 527 nm and 1053 nm are 25 J/cm2, 34 J/cm2 and 63 J/cm2, respectively. The high LIDT of the coatings can be mainly attributed to the large band gap of MgF2. The antireflective coatings may be potentially applied in the high-powered lasers.