热蒸发技术制备梯度折射率薄膜的研究  

Study on Gradient Index Films Prepared by Thermal Evaporation Technology

作　　者：刘祺 徐均琪[1] 苏俊宏[1] 韩刚 李阳[1] 袁松松 LIU Qi;XU Jun-qi;SU Jun-hong;HAN Gang;LI Yang;YUAN Song-song(Shaanxi Province Key Laboratory of Thin Films Technology and Optical Test,Xi′an Technological University,Xi′an 710021,China;Xi′an Northern Photoelectric Co.,Ltd.,Xi′an 710043,China)

机构地区：[1]西安工业大学陕西省薄膜技术与光学检测重点实验室,陕西西安710021 [2]西安北方光电有限公司,陕西西安710043

出　　处：《真空》2022年第6期22-28,共7页Vacuum

基　　金：陕西省国际科技合作与交流计划资助项目(2018KWZ-02);西安市智能探视感知重点实验室项目(201805061ZD12CG45)。

摘　　要：采用双源共蒸MgF_(2)和ZnS的方法,通过控制两种材料的沉积速率比,获得了制备梯度折射率薄膜所需要的中间折射率材料。将G|HL|A双层减反膜梯度化为5层,保持总光学厚度不变,制备了折射率沿厚度方向按1.91、1.77、1.64、1.48、1.38(波长532nm)渐变的梯度折射率减反膜。对所有薄膜样品进行了光学和激光损伤特性的测试,结果表明:双源共蒸MgF_(2)和ZnS所得复合膜的折射率,及两种材料的沉积速率比,满足Drude理论导出的关系式;复合膜的折射率符合正常色散,除折射率为1.91的复合膜吸收较大(532nm处消光系数为0.01),其余复合膜都表现出较小的吸收(532nm处消光系数均小于0.002);用100mJ能量激光辐照所有单层膜样品,折射率为1.64的复合膜激光损伤程度最小,表现出比单组分MgF_(2)和ZnS薄膜更高的抗激光损伤能力;将双层减反膜等效为折射率梯度渐变的5层后,减反射带宽从205nm扩展到了380nm,激光损伤阈值从2.0J/cm^(2)提高到了3.7J/cm^(2),提高了85%。综上可知,采用双源共蒸技术,通过调节两种材料蒸发速率比,制备折射率按一定规律渐变的薄膜是可行的。只要两种材料比例合适,利用共蒸技术可获得抗激光损伤性能高于单组分薄膜的复合膜。梯度折射率减反膜可拥有比双层减反膜更好的光学特性和更高的激光损伤阈值。The intermediate refractive index material required for preparing gradient refractive index films is obtained by adopting the method of dual-source co-evaporation of MgF_(2) and ZnS and controlling the deposition rate ratio of both materials.The G|HL|A double-layer anti-reflection film is graded into 5 layers,and keeping the total optical thickness unchanged,the gradient index anti-reflection film with a gradient of 1.91,1.77,1.64,1.48,and 1.38(wavelength of 532nm)along the thickness direction is prepared.All samples are tested for optical and laser damage characteristics.The results show that the refractive index of the composite film obtained by double source co-evaporation of MgF_(2) and ZnS and the deposition rate ratio of the two materials satisfy the relationship deduced according to Drude theory.The refractive index of the composite film accords with the normal dispersion.Except for the material with the refractive index of 1.91,of which the absorption is large(extinction coefficient at 532nm is 0.01),the other composites show small absorption(extinction coefficients at 532nm are less than 0.002).When all the monolayer films are irradiated with 100mJ energy laser,the composite film with the refractive index of 1.64 has the lowest laser damage,showing higher resistance to laser damage than single-component ZnS and MgF_(2) films.When the double-layer anti-reflection film is equivalent to five layers with graded refractive index,the passband range is extended from 205nm to 380nm,and the laser damage threshold is increased from 2.0J/cm^(2) to 3.7J/cm^(2),which is increased by 85%.It can be seen that it is feasible to prepare thin films with graded refractive index by adjusting the evaporation rate ratio of the two materials.As long as the ratio of the two materials is appropriate,using co-evaporation technology can obtain a composite film that has higher resistance to laser damage than a single-component film.The graded index anti-reflection film has better optical properties and higher laser damage threshold

关 键 词：梯度折射率 双源共蒸 减反膜 复合膜 激光损伤阈值 

分 类 号：O484[理学—固体物理] TB43[理学—物理]