Organosilicone composite antireflective (AR) coating was successfully prepared for Ti-sapphire crystals by sol-gel process from precursors of tetraethoxysilane [Si(OC2H5)4, TEOS] and methyltriethoxysilane [CH3Si(OC2H5)3, MTEOS]. This AR coating possessed prominent AR effect within the output waveband (750～850 nm) of Ti-sapphire laser with average transmission above 98.6%, and its surface homogeneity met the requirements of the laser wavefront. The laser induced damage threshold (LIDT) of 2.2 J/cm2 was obtained at 800 nm with the pulse duration of 300 ps for this AR coating on Ti-sapphire crystals, which made it suitable for the optics of ultrashort pulse pico- and femtosecond high power lasers. Further, investigations on the performance of coating solution showed that the viscosity and coating refractive index both increased along with MTEOS prepolymer content, and effect of bake temperature on the latter was very small.

以硅酸四乙酯(TEOS)和甲基三乙氧基硅烷(MTEOS)为前驱材料,用溶胶-凝胶(sol-gel)方法在钛宝石表面制备得到均匀性良好且具有高激光损伤阈值的有机硅复合凝胶增透膜。膜层在钛宝石激光器输出波段(750～850 nm)的增透效果显著,其平均透过率超过98.6%;激光破坏阈值为2.2 J/cm2(800 nm,300 ps);膜层表面均匀性达到激光波面的要求,在皮秒、飞秒超短脉冲高功率激光领域具有应用价值。溶胶的性能测试结果表明,溶胶粘度和成膜折射率均随溶液中CH3SiO1.5溶胶体含量的增加而增大,而膜层折射率受烘烤温度影响较小。