倍半氧化物激光材料低损伤加工研究
文献类型：学位论文
| 作者 | 沈冯峰 |
| 文献子类 | 硕士 |
| 导师 | 徐学科 |
| 关键词 | 光学加工 Optical processing 碟片激光器 thin-disk laser YAG YAG Yb:LuScO3 Yb:LuScO3 激光损伤阈值 laser damage threshold |
| 其他题名 | Study on Low-Damage Processing of Sesquioxide Laser Materials |
| 英文摘要 | 倍半氧化物激光晶体，与传统的YAG激光晶体相比，在热导率，声子能量，晶体场方面具有明显优势，是目前最有发展前景的激光增益介质之一。作为增益介质的倍半氧化物激光晶体，应用于高功率、高能量的激光系统中，对倍半氧化物的光学加工工艺提出了非常高的要求。为此本文针对倍半氧化物激光晶体的高精度低缺陷光学加工进行了系统性研究。主要从以下几个方面开展研究工作： 前期研究了物化特性相近的YAG激光晶体的超精密光学加工工艺，从研磨到粗抛再到精抛。研磨阶段，使用不同粒径的B4C磨料和铸铁盘，实现YAG样品表面损伤层和尺寸精度的有效控制；粗抛阶段，使用金刚石微粉和树脂铜盘，去除研磨阶段带来的表面损伤和面形精度；精抛阶段，使用Al2O3抛光液和沥青抛光模，最终经过检测，表面粗糙度为0.346 nm，反射面形为0.2 λ（λ=632.8 nm）。在脉宽为9.0 ns的1064 nm激光条件下，加工好的YAG晶体的激光损伤阈值为6.1 J/cm2。 基于YAG晶体的加工数据，成功选择了Yb:LuScO3晶体加工工艺参数和加工路线。在Yb:LuScO3晶体加工中，由于样品尺寸较小，采用保护垫料拼接的方法，建立了不同保护垫料拼接下样品所受应力分布仿真模型。使用多物理场仿真软件COMSOL Multiphysics进行仿真，最终选择YAG晶体作为保护垫料。使用YAG晶体作为保护垫料，加工过程中样品所受应力分布均匀，可以避免发生崩边，破碎等边缘问题。粗抛阶段，使用树脂铜盘作为抛光垫，分析了树脂铜盘的作用。树脂铜盘的硬度比沥青抛光模大，抛光速率较快，面形变化较小，便于耦合精抛阶段。精抛阶段使用Al2O3抛光粉和沥青抛光模，实现了Yb:LuScO3晶体的超精密光学加工。 最终样品表面粗糙度为0.296 nm，反射面形为0.084 λ。在激光二极管泵浦下，泵浦功率为15.2 W，输出功率为8.3 W，激光斜效率为58%的1086 nm激光输出。; Sesquioxide laser crystal is rapidly developed in modern material field. Compared with YAG laser crystal, it has significant advantages such as excellent thermal conductivity, comparably low phonon energies and a strong crystal field. So the sesquioxide laser crystal has become a very promising laser gain medium. It has been successfully applied to thin-disk laser, effectively eliminating the thermal lens effect and producing better beam quality. As the gain medium, the sesquioxide laser crystal is used in high-power and high-energy laser system, it’s required to has good surface figure and surface roughness. For this reason, high-precision and low-damage optical processing on sesquioxide laser crystal had been studied. In this thesis, researches have been carried out on the following aspects: The ultra-precision optical processing of YAG laser crystal was studied. During the lapping processing, B4C abrasives with different particle sizes and cast iron pad were used to remove surface damage after lapping stage. In the rough polishing stage, diamond powder and copper resin pad were used to remove surface damage caused by the lapping stage. The Al2O3 polishing slurry and pitch polishing pad were used in fine polishing. Finally, the surface roughness was 0.346 nm, the flatness was 0.2 λ, and the laser damage threshold was 6.1J/cm2. According to the YAG laser crystal processing, the processing parameters of Yb:LuScO3 laser crystal were obtained. In the processing of Yb:LuScO3 laser crystal, the method of protective padding is adopted beacause the sample size is small. A simulation model for the stress distribution of sample with different protective padding was established. Using COMSOL MULTIPHYSICS simulation software, YAG crystal was finally selected as the protective padding. The stress distribution of sample during processing is even, the edge problems such as chipping and crushing can be avoided. In the rough polishing processing, the material removal mechanism of copper resin pad was analyzed. The hardness of copper resin pad is greater than pitch polishing pad, which facilitates the coupling fine polishing processing and realizes high-precision and low-damage optical processing. Finally, the results show that the RMS value of the surface roughness less than 0.3 nm and processed surface flatness value less than λ/10. Up to 8.3 W of output power and 58% of slope efficiency were obtained with a diode laser pump source. Thereby Yb:LuScO3 crystal surface of high-precision and high-quality can be obtained by the processing. |
| 学科主题 | 光学工程 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/31066]  |
| 专题 | 中国科学院上海光学精密机械研究所 |
| 作者单位 | 中国科学院上海光学精密机械研究所 |
| 推荐引用方式 GB/T 7714 | 沈冯峰. 倍半氧化物激光材料低损伤加工研究[D]. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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