| 题名 | 基于LuAG的复合激光陶瓷研究 |
| 作者 | 张攀德 |
| 文献子类 | 博士 |
| 导师 | 张龙 |
| 关键词 | 激光陶瓷，Nd:LuAG，复合激光陶瓷，YAG/Nd:LuAG，Sm包边Nd:LuAG，Sm包边Cr,Nd:LuAG laser ceramic, Nd:LuAG, composite laser ceramic, YAG/Nd:LuAG,edge cladding |
| 其他题名 | Studies of composite laser ceramics based on LuAG |
| 英文摘要 | 激光技术的发展历程表明“一代材料、一代器件、一代技术”，激光材料是激光技术发展的核心和基础。目前制约固体激光系统向更高效率、更高功率、更大能量发展的核心问题是增益介质能量转换效率低、热管理能力差及 ASE 效应等问题。激光透明陶瓷材料的制备优势有望突破固体激光面临的热管理瓶颈、解决 ASE 效应、 并有效提升能量转换效率，已经成为满足高重频大能量激光系统的主要发展增益介质之一。 Nd:LuAG 激光陶瓷材料具有高热导率（~8 W/m·K）、 较长荧光寿命（> 220μs）和合适的发射截面(9.7×10-20 cm2)，可满足重频固体激光系统对增益介质的需求。 同时， 其约 2 J/cm2 的饱和通量既可以保证激光系统数倍增益介质饱和通量运行， 实现高效能量提取， 又可保证光学元件工作在损伤阈值以下，降低激光系统及其光学元件损坏的风险和系统的维护成本，提高激光系统的运行效率。但是大尺寸 Nd:LuAG 激光陶瓷材料仍然面临着泵浦效率较低、横向 ASE 效应严重、热管理能力偏低等问题。基于此， 本论文在研究优化 Nd:LuAG 透明陶瓷制备工艺的基础上，通过能带设计， 提升增益介质泵浦效率： 通过 Cr 离子敏化，材料荧光寿命由 Nd:LuAG 激光陶瓷的~220 μs 增长到~600 μs，吸收带宽由760、 808 nm 等几个窄吸收峰拓宽为 350-740 nm 的宽吸收带， 有效提高材料储能能力及泵浦效率； 通过复合结构设计， 提升材料热管理性能： 采用直接热键合方法和单晶陶瓷化方法研究制备了 YAG/Nd:LuAG 基系列复合激光陶瓷，有效提升材料热管理性能， 并为波导结构、薄片激光器增益介质和方形包边结构的研制奠定一定的理论和实验基础； 通过包边结构设计，消除增益介质 ASE 效应： 利用 Sm 离子对材料进行包边处理，有效吸收激光增益介质中的横向光，解决大口径激光增益材料 ASE 效应和寄生震荡现象。 基于上述研究内容， 本论文主要包括以下四个方面： 1. Nd:LuAG 激光陶瓷制备工艺改进及材料性能研究 通过烧结助剂 SiO2 和 MgO 对样品晶界自由能进行调控，实现晶界迁移速度和气孔迁移速率相匹配，从而达到真空烧结样品气孔尺寸和气孔位置的控制，并且利用工艺改进后的真空烧结+热等静压两步烧结法成功制备晶粒微化、散射损耗仅 0.2% cm-1 的高光学质量 Nd:LuAG 激光陶瓷。 利用所制备材料进行激光实验，实现 2.5W斜效率 42.1%的连续激光输出和 100 Hz 单脉冲能量为 11 mJ、脉冲宽度 7 ns、 脉冲峰值功率 1.57 MW 的脉冲激光输出。 2. Cr,Nd:LuAG 激光陶瓷制备与研究 基于“能带工程”及能量传递途径和效率的理论推演，开展 Cr 敏化 Nd:LuAG激光陶瓷体系材料研究。 通过对 Cr 敏化Nd:LuAG 激光陶瓷中敏化离子浓度调整，实现敏化离子与激活离子之间的高效能量传递、最大限度提高泵浦效率。利用温度、助剂等调控陶瓷晶界自由能，成功制备了晶粒微化、气孔率低、散射损耗仅 0.2% cm-1 的高光学质量 Cr 敏化 Nd:LuAG 激光陶瓷。在此基础上，研究了该体系材料的激光性能，实现了多泵浦波段的 1064 nm 激光输出。验证了材料上能级能量的有效传递。 3. YAG/Nd:LuAG 基复合激光陶瓷体系的制备与研究 以解决固体激光系统中热管理能力差的问题为出发点，深入研究相关问题产生机理，通过材料结构设计， 利用一步热键合法成功制备 YAG 陶瓷/Nd:LuAG基激光陶瓷体系材料， 系统研究键合机理、键合区域显微结构，并利用首次提出的“单晶陶瓷化”方案成功制备了高质量 YAG 单晶/Nd:LuAG 基激光陶瓷体系， 提升了键合材料质量，并有效提升材料热管理性能。 4. Sm:LuAG 包边 Nd:LuAG 基激光陶瓷体系的制备与研究 通过结构设计，采用对 1064 nm 有强吸收的 Sm 离子对大口径圆形Nd:LuAG 基材料进行包边，以解决大口径 Nd:LuAG 基激光陶瓷横向 ASE 效应。利用一步成型法对所设计材料进行成型， 利用两步烧结法实现了高质量的增益中心为 φ50 mm 包边厚度为 7 mm 的复合激光陶瓷制备，并对材料相关性质进行研究。; The development history of laser technology shows that "one generation of materials, one generation device, and then one generation technology". Until now, laser material is still the core and foundation in the development of solid laser technology. At present, the key problems that restrict the development of solid laser system to higher efficiency, higher power and greater energy are the problems of poor thermal management capability, low energy conversion efficiency and ASE effect. The laser ceramics can improve thermal management and slove the ASE effect of solid state laser, and can effectively improve the energy conversion efficiency. Thus, laser ceramic has become one of the most important laser materials, which can meet the requests of high frequency and high energy solid laser systems. Nd3+-doped LuAG has many obvious advantages, such as a moderate emission cross section (~ 9.7×10?20 cm2), a high thermal conductivity (~ 8 W/(m·K)), moderate saturation fluence (2 J/cm2) and long effective fluorescence lifetime (>220 μs). Thus, it has potential applications in ICF as gain material. However, large size Nd:LuAG ceramics still have poor thermal management capability, low energy conversion efficiency and ASE effect. Thus, we should study composite laser materials based on Nd:LuAG by our preparation technology of laser ceramics. Firstly, in order to improve the pump effeciency and energy storage capacity of Nd:LuAG, we designed and fabricated Cr-sensitized Nd:LuAG laser ceramics with excellent optical properties by two steps sintering method. The absorption bands from 300 to 700 nm of Cr(0.15 at.%),Nd(1 at.%):LuAG were effectively expanded by codoping Cr3+ ions. And the effective fluorescence lifetime of Cr(0.15 at.%),Nd(1 at.%):LuAG was about 600 μs. Secondly, to improve the thermal management capability of Nd:LuAG ceramic, we designed YAG/Nd:LuAG composite laser ceramics and fabricated them with excellent optical properties. Thirdly, in order to solve the ASE effect of big size Nd:LuAG ceramics, we designed Sm edge cladded Nd:LuAG composite laser ceramics and fabricated them with excellent optical properties. Above all, this dissertation mainly includes the following four parts: 1. Improvement of laser ceramics preparation technology and studies of Nd:LuAG ceramic properties In our study, Nd:LuAG ceramics were prepared by vacuum sintering plus hot isostatic pressing (HIP) sintering method. SiO2 and MgO were used as sintering additives to improve the optical qualities of Nd:LuAG ceramics. Good optical quality Nd:LuAG laser ceramics with low scattering loss (0.2% cm-1) were prepared. A diode-end-pumped Nd:LuAG ceramic laser experiment was demonstrated. CW output power of 2.5 W was obtained, corresponding to optical conversion efficiency of 27.5% and slope efficiency of 42.1%. For the 100 Hz E-O Q-switched, the shortest pulse width and the largest pulse energy were measured to be 7 ns and 11 mJ. The peak power achieved 1.57 MW. 2. The preparation and studies of Cr,Nd:LuAG ceramics High-quality Cr,Nd:LuAG laser ceramics were successfully fabricated by annealing sintered samples. Annealing completely eliminated the nearinfrared absorption, and the in-line transmittance of the specimen reached 84.38% near the lasing wavelength of 1064 nm, which is very close to the theoretical value for LuAG laser ceramics. Furthermore, the effective fluorescence lifetime of Cr,Nd:LuAG ceramics significantly increased to 553.8 μs when pumped at 440 nm. Moreover, the laser performance of the system is studied, and the output of the 1064 nm laser was realized by pumped at 449 nm and 808 nm, which certified the effective energy transfer from Cr3+ ions to Nd3+ ions. 3. The preparation and studies of YAG/Crx,Ndy:LuAG composite laser materials Composite YAG/Nd:LuAG laser materials were obtained through thermal bonding process and the ceramization of YAG single crystals from the original bonding interfaces of green bodies (optical contacted YAG crystal/Nd:LuAG ceramic materials). The morphology, microstructural characteristics, and optical properties of the composite materials were studied. The results indicated that Nd:LuAG and YAG were completely combined without bonding interfaces. It was pore-free at the original contacting interface of the YAG/Nd:LuAG transparent material and the in-line transmittance of the specimen reached 84% near the lasing wavelength of 1064 nm, which is very close to the theoretical value. This suggests that ceramization of YAG single crystals as in this study is a promising way to fabricate composite YAG/Nd:LuAG transparent materials. 4. The preparation and studies of Sm edge cladded Crx,Ndy: LuAG composite laser ceramics The ASE effect of large diameter Crx,Ndy:LuAG laser ceramics was solved by Sm ion edge cladding. High quality composite laser ceramics with large diameter were prepared by vacuum sintering plus hot isostatic pressing (HIP) sintering method. And the related properties of the materials were studied. |
| 学科主题 | 材料学 |
| 内容类型 | 学位论文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/31028]  |
| 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 | 张攀德. 基于LuAG的复合激光陶瓷研究[D]. |
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