Protective coatings for large-sized KDP crystals

Abstract

Large size potassium dihydrogen phosphate (KDP) crystals were coated with a polymethyltriethoxysilane (PMTES) coating for environmental protection. The optical property and environmentally protective ability of coatings are investigated. The coatings have high transmission in the range of 200 to 1100 nm. On the conditions of wavelength 1.054 micrometer and a pulse length 1 ns, the laser damage threshold of the coating is higher than 8.4 J/cm2. It is found that the thresholds of the coatings are not obvious change below 80 degrees Celsius and increase with the increasing of the cured temperature. The fogging phenomenon of the KDP crystals coated with PMTES coating has not been observed after more than one year in ambient atmosphere.