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题名	高性能紫外光学薄膜元件研制
作者	李煦
学位类别	硕士
答辩日期	2013
授予单位	中国科学院上海光学精密机械研究所
导师	张伟丽
关键词	355 nm，激光损伤阈值，高反膜
其他题名	Design and Preparation of High Performance UV Optical Thin Film Components
中文摘要	在高功率激光系统中，光学薄膜的激光损伤阈值(LIDT)一直是影响功率输出的关键因素。为了提高光学薄膜材料的激光损伤阈值，国内外已经在激光损伤机理、基底清洁工艺、薄膜制备工艺、激光预处理工艺和后处理技术等方面展开了一些研究。 355 nm波段常用的光学薄膜材料包括LaF3、MgF2、AlF3等氟化物和Al2O3、Sc2O3、HfO2、SiO2等氧化物。本文采用电子束蒸发和电阻热蒸发两种方式制备了不同的单层薄膜样品，明确了影响单层膜在355 nm性质的主要因素，并以此为基础设计制备了不同组合的高反膜。 系统分析了沉积条件（包括基底温度、沉积速率、工作气压等）对AlF3、LaF3及MgF2单层膜的光学常数、化学组成以及激光损伤阈值的影响，并通过基底的酸洗处理、蒸发速率的稳定控制等方式优化单层膜的性能。通过分析工作气压对AlF3单层膜的影响，发现在一定氧分压下制备的AlF3单层膜具有更低的消光系数和更高的激光损伤阈值。在工艺优化的基础上，设计制备了LaF3/AlF3高反膜，并分析了SiO2内保护层对氟化物高反膜的残余应力以及抗激光损伤性能的影响。包含SiO2内保护层的10周期LaF3/AlF3高反膜损伤阈值达20J/cm2（355 nm，8 ns，下同）。 通过改善氧化物的蒸发特性，优化了Al2O3与HfO2单层膜的制备工艺，并将其应用于氧化物高反膜。SiO2内、外保护层均对Al2O3/SiO2高反膜的抗激光损伤性能有优化作用，制备的薄膜样品损伤阈值在10J/cm2以上，在氧化物膜系中属于较高的水平。通过分别改变HfO2和SiO2膜层的工艺参数，优化了HfO2/SiO2高反膜的性能，制备出了中心波长透过率低于1%，损伤阈值高于5J/cm2的薄膜样品。 高阈值的氟化物高反膜存在较大的应力问题，而低应力的氧化物高反膜阈值较低。为了充分结合两者的优点，设计制备了Al2O3/AlF3、Al2O3/SiO2/LaF3/AlF3、Al2O3/AlF3/LaF3/AlF3和HfO2/SiO2/LaF3/AlF3组合高反膜，并表征了其光学性质、激光损伤性能和微观形貌信息。组合膜系在得到较高反射率的同时有效避免了裂纹的出现，损伤阈值在12J/cm2以上。 分析了SiO2中间层对HfO2/SiO2/LaF3/AlF3组合高反膜的影响。SiO2虚设层的主要作用表现在抑制其下方的氧化物缺陷引起的破坏，以及提高其上层氟化物膜层的质量，并降低薄膜的宏观应力，因此具有远优于传统组合高反膜的性能。制备的组合高反膜损伤阈值高于18J/cm2，为制备高性能355 nm高反膜提供了一种可行的制备方案。
英文摘要	The laser-induced damage threshold (LIDT) of optical thin film components is a key factor that influencing the delivered power of high power laser systems. In order to improve the LIDT of optical thin films, intense researches have been conducted on the laser damage mechanism, substrate cleaning, thin film fabrication technique, laser conditioning, and post treatment process. Fluorides including LaF3, MgF2, AlF3 and oxides such as Al2O3、Sc2O3、HfO2、SiO2 are commonly used in the 355 nm regime. Monolayer thin films were prepared by electron beam evaporation and resistant heating technique, and the major factors that influence the properties at 355 nm were revealed. Based on those results, 355 nm high-reflective (HR) coatings with various stack formula were designed and fabricated. The influence of deposition parameters (such as deposition rate, working pressure, and substrate temperature) on the optical constants, chemical composite, and LIDT of AlF3, LaF3, MgF2 monolayers were analyzed systemically. In the study of the influence of working pressure on the properties of AlF3 thin films, certain oxygen pressure was proved to be beneficial the reduction of extinction coefficient and the increase of LIDT. LaF3/AlF3 HR coatings were prepared and the influence of undercoat on the residual stress and laser damage resistance were studied. The LIDT of 10-layer-pair LaF3/AlF3 HR coatings with undercoat reached as high as 20J/cm2 (355 nm, 8 ns). The properties of Al2O3 and HfO2 monolayers were optimized by meliorating the deposition parameters, and oxide HR coatings were manufactured. SiO2 undercoat and overcoat was proved to be beneficial to the properties of Al2O3/SiO2 HR coatings, and the LIDT of which is higher than 10J/cm2. The processing parameters of HfO2 and SiO2 layers were adjusted in HfO2/SiO2 HR coatings. The central wavelength transmittance is lower than 1%, and the LIDT is higher than 5J/cm2. One serious dichotomy exists between the performance of oxides and fluorides. The laser resistant fluorides have high tensile stress, while the oxides with low stress have low LIDT. In order to combine the advantages of both materials, double stack HR coatings based on Al2O3/AlF3, Al2O3/SiO2/LaF3/AlF3, Al2O3/AlF3/LaF3/AlF3 and HfO2/SiO2/LaF3/AlF3 were prepared, and their laser resistance and damage morphology were characterized. The double stack design could reach relatively high reflectance and avoid crack, and the LIDT reached 12 J/cm2. The performance of HfO2/SiO2/LaF3/AlF3 double stack HR coatings was optimized by introducing SiO2 interlayers to the interface between oxides and fluorides. The interlayer benefits the coatings by inhibiting the damage in oxide layers from growing, improving the quality of fluoride stacks, and reducing the residual stress, thus resulting in double stack HR coatings far exceeding the performance of conventional ones.
语种	中文
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/16780]
专题	上海光学精密机械研究所_学位论文
推荐引用方式 GB/T 7714	李煦. 高性能紫外光学薄膜元件研制[D]. 中国科学院上海光学精密机械研究所. 2013.

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