The transmission of porous silica antireflective (AR) coating after heat treatment is correlative with environmental relative humidity because there are many Si-OH hydrophilic groups on the coating surface. The aim of the experiment is to add hydrophobic groups to the coating to enhance its hydrophobic performance and improve its stability. In this paper, Si-CH3 non-polar hydrophobic groups appear on the coating surface through dash with organic silica, raising its hydrophobic performance, and thus the stability and life of AR coating are improved greatly. When the molar content of organic silica (Si-CH3) is 17.5% (mass concentration 0.35%), the antireflectivity of coatings is high, while the performance of high laser damage threshold is not affected.

膜层稳定性对于激光器能否长期稳定使用极为重要。多孔SiO2减反膜经热处理后，结构中还存在许多Si-OH亲水基团，透过率稳定性受环境相对湿度的影响较大。向膜层中掺入有机硅，添加疏水基团，提高了膜层的疏水性，增强了膜层的透过率稳定性。膜层中加了Si-CH3疏水基团，膜层的疏水性大大提高;当Si-CH3与二氧化硅悬胶体中的Si的摩尔比为1/5.7时，即Si-CH3质量分数为0.35%时的二氧化硅膜层，其减反效果好，疏水性也高，从而大幅度提高了膜层的透过率稳定性，延长了膜层的寿命，对二氧化硅膜层具有高激光损伤阈值的性能没有影响。