Using methyl triethoxysilicane as precursor, a moisture-resistant coating for neodymium-doped laser glass was developed by the sol-gel process. Colloidal silica was added in coating solution as modifier. The refractive index of this coating varied from 1.31 to 1.42. A porous antireflective (AR) silica coating with the index of 1.27 was coated on the moisture-resistant coating surface. The two-layer coating possessed transmission up to 99.1% at wavelength of 966 nm, surface root-mean-square (RMS) roughness of 1.245 nm, and roughness of average (RA) of 0.961 nm. In the case of laser of 1053-nm laser wavelength and 1-ns pulse duration, the damage threshold of the two-layer coatings was more than 15 J/cm2.
