KDP类晶体缺陷及抗激光损伤性能研究
文献类型：学位论文
| 作者 | 常俊秀 |
| 学位类别 | 硕士 |
| 答辩日期 | 2015 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 邵建达 |
| 关键词 | KDP类晶体 缺陷 激光损伤 |
| 其他题名 | Properties of defects and laser induced damages in KDP-type crystal |
| 中文摘要 | KDP类晶体是一类性能优良的多功能晶体，它具有良好的电光性和非线性，能够生长大尺寸单晶。因而，KDP类晶体目前是高功率激光装置不可替代的非线性晶体材料，用于制作Pockel’s和频率转换器件。在高功率激光器中，KDP类晶体的激光损伤问题制约着激光系统的运行通量，尤其是倍频和混频晶体激光损伤问题突出。晶体生长过程中引入的各类缺陷可能是诱导晶体材料激光损伤的主要原因之一。缺陷的存在可能破坏晶体完整性，增加其对激光脉冲的吸收，并进而影响晶体材料的光学性能。本文以提高KDP类晶体激光损伤阈值为目的，对KDP晶体材料的缺陷进行了探测、表征和分析，并研究了缺陷特性与材料抗激光损伤性能的关系，为进一步改进晶体材料生长工艺及提高晶体性能提供了重要依据和参考。主要工作和结果如下： 1、KDP类晶体材料缺陷的探测与表征，获得三类散射缺陷的特性。 采用激光散射探测技术探测到KDP类晶体的三类散射缺陷：微米级缺陷、亚微米级缺陷、散射带缺陷。根据微米级缺陷和亚微米级缺陷的尺寸，采取不同的实验方案分别对其进行表征。使用光学显微镜和二次离子质谱仪研究微米级缺陷，结果显示微米级缺陷为几十微米尺寸的含杂质的液相包裹体；使用透射电子显微镜和x射线能谱仪研究亚微米级缺陷，结果显示其为无杂质的亚微米尺寸液相包裹体。 2、KDP类晶体激光损伤机理及诱导源研究。 实验观察到KDP类晶体微米级缺陷和亚微米级缺陷与激光损伤有关，采用FDTD solution模拟计算缺陷附近激光能量分布。结果显示，355nm激光辐照下KDP类晶体中微米级缺陷、亚微米级缺陷附近激光能量密度增强。研究KDP类晶体激光损伤随着激光脉冲能量密度、脉宽增加的变化趋势，分析得到激光损伤机理：激光损伤包括熔融、等离子体烧蚀、“微爆炸”三个过程。对比355nm、1064nm激光损伤特性，推测其诱导源：H缺陷可能是355nm激光损伤的主要诱导源之一，同时不是1064nm激光损伤点的主要诱导源。 |
| 英文摘要 | KDP-type crystal is a kind of multifunctional crystal with high electro-optical and nonlinearity. Also KDP-type crystal can be grown into large-aperture. Therefore it is the only choice for the Pockel’s and frequency conversion in high power laser system. KDP-type crystal, especially which are used as doubling and THG crystals in high power laser system, suffers from laser damage.. Defects introduced by grown progress are suggested to be one reason that inducing laser damage. Defects weaken the crystalline of KDP-type crystal, and facilitate photons absorption. It will affect the optical performance of KDP-type crystal. In this paper, bulk defects were characterized, aimed at improving the damage threshold of KDP-type crystal. And the laser damages were studied. In detail, efforts were made in the following aspects: 1 The detection and characterization of three kinds of defects in KDP-type crystal Three kinds of scattering defects were detected in KDP-type crystal, which were named micron-scale defect, submicron-scale defect and scattering band defect. Different methods were employed depending on the size of defects for further analysis. Micron-scale defects were characterized by optical microscope and SIMS, and they were found to be liquid inclusions containing impurities. Their sizes were tens of micrometers. Submicron-scale defects were studied by TEM and EDS. Submicron-scale defects were found to be liquid inclusions without impurities, the sizes of which ranged from tens to hundreds of nanometers. 2 The characterization of laser induced damages of KDP-type crystal, and the relationship between defects and damages. The laser damage threshold of KDP-type crystal was found to be related to micron-scale defect and submicron-scale defect. The laser energy distributions around defects in KDP-type crystal were analyzed by FDTD solution. Results showed that laser energy was enhanced around micron-scale defect and submicron-scale defect, which might induce laser damage. The laser induced damages of KDP-type crystal were characterized. Three steps were suggested in laser damage, such as melting, plasma and "micron explosion". H defects might be a main reason for 355nm laser damage, while not for 1064nm laser damage. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16920]  |
| 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 | 常俊秀. KDP类晶体缺陷及抗激光损伤性能研究[D]. 中国科学院上海光学精密机械研究所. 2015. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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