光谱色散平滑技术的研究
文献类型：学位论文
| 作者 | 周申蕾 |
| 学位类别 | 博士 |
| 答辩日期 | 2006 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 林尊琪 |
| 关键词 | 辐照均匀性 光谱色散平滑 透镜列阵 位相调制器 |
| 其他题名 | The Technology of Smoothing by Spectral Dispersion |
| 中文摘要 | 惯性约束聚变、X射线激光及状态方程的研究等是当今重大基础科研课题，有着非常重要的科学意义和国防应用价值。在这些研究中都要求入射激光束均匀辐地辐照在特定靶面区域，而靶面焦斑的均匀性将直接影响到物理实验目标的实现。因此实现靶面特定区域的均匀辐照就显得非常重要，但由于激光具有很强的时空相干性，最大限度实现激光靶面时空均匀化已成为国际上前沿领域的重大难题之一。本文着重对光谱色散平滑 (Smoothing by Spectral Dispersion：SSD) 技术作系统的分析和研究，主要工作包括： 1． 从空域和谱域两方面对光谱色散平滑技术作理论分析，得到其输出光场的表达式，并结合空间域平滑技术对光谱色散平滑技术的平滑特性模拟计算和分析，发现由于存在着周期位相调制，导致焦斑的不均匀性随时间也有周期变化，但其变化总体上仍是一个下降趋势；具体分析了该技术中的参量变化对焦斑均匀性的影响。 2． 利用广义衍射理论和空域Collins公式，首次推导出光谱色散平滑下的光束通过不同光学系统后的传输公式，重点分析了自由传输和透镜焦点处的光场变化，并结合实验结果比较研究其空间传输特性；在一般脉冲放大器理论的基础上结合放大介质的跃迁谱线线型函数，推导出周期位相调制条件下的光束放大后时间波形的递推关系解，数值分析了放大后时间波形的变化，计算结果与实验吻合。该项工作发展了一般脉冲放大器的理论，同时也为抑制该放大过程中出现的PM-AM效应提供了一种分析方法。 3． 从符合高功率激光系统的应用出发，首次在国内开展对光谱色散平滑技术的实验研究，详细分析了研究结果；国际上首次提出光谱色散平滑技术与透镜列阵技术联用方案实现靶面均匀辐照，并与其它应用方案做了比较分析。计算结果表明，在与透镜列阵的联用后，可以很好的改善焦斑的均匀性，选择合适的谱色散平滑技术中的参数能弥补透镜列阵方案在大F数靶镜时的缺陷；发现应用该方案能明显降低对入射近场初始边界条件的苛刻要求，显示出应用SSD＋LA组合方案相对于其它方案的优越性。同时实验比较了不同平滑方案下焦斑特性。 4． 对光谱平滑技术中极为关键的元器件——准速度匹配下周期畴反转位相调制器从原理、设计及制作工艺方面作了详细的论述和分析，并给出调制器的测试、分析结果，讨论了元件继续发展的方向。对其它相关器件的要求也作了说明。本项工作的完成和实际应用填补了国内相关领域的空白，有力推动光谱色散平滑技术及相关研究工作的开展。 |
| 英文摘要 | Inertial confinement fusion, X-ray lasers and Equation of State are some of the fundamental researches fields today, which is very important for science and national defence technology. In the experiments of these researches, energy of the incident laser beams must be focused onto the target specific surface very uniformity, and the success of these experiments is depended on the irradiation uniformity. However, the maximum realization of uniform irradiation is one of the unsolved problems of frontier research in the world because of the spatial and temporal coherence of laser. In this thesis, the technology of smoothing by spectral dispersion (SSD) is analyzed and studied; the main works are summarized as follows. 1. The expressions of output laser in spatial-domain and frequency-domain are obtained based on the principle of SSD, and the character of SSD combining with spatial smoothing technology in the process of beam smoothing is also analyzed by numerical simulation. Though the irradiation nonuniformity of focal pattern will vary with time periodically when a period electronic field is applied in phase modulation, the trend of this change is still drop. The contributions of parameters in SSD to irradiation uniformity are also studied by simulation. 2. The propagation expressions of a SSD beam pass through different optical systems are derived from generalized diffraction theory and Collins equation, and the changes and features of beam including free transmissions and focal plane are analyzed numerically for the first time, which is compared with the results of earlier experiment. Furthermore, a physical model of a periodic phase modulating laser beam amplifying are created from the general theory of pulse laser amplifying and the transition line-shape of the media. Some simulations are made to study the changes of amplified laser pulse, and the results are also consistent with experiments. This work not only develops the theory of laser amplifying, but also provides a method of studying the effect of PM-AM during the amplifying. 3. The study of SSD experiment was made for the first time in China and analyzed in detail based on requirements of application on high power laser system. The method of combining Lens array (LA) with SSD is introduced first in the world to realize uniform irradiation on target plane, and the work of comparing with other smoothing methods is made by numerical simulation and experiments. The results show that the effect of improving irradiation uniformity by this method is obviously and the application of SSD with suitable parameters can cover the shortage of LA used with a big F-number focal lens. The hard requirements of initial near-field boundary conditions of incidence are decreased greatly in the smoothing method of LA and SSD, which is superior to others. 4. The electro-optical phase modulator with quasi-velocity-matched domain-inverted technology, which is a very important element in SSD, is introduced and studied from principle, design and fabrication in detail. Some tests of this modulator are taken and the developments in the future are also discussed. Some associated elements in SSD are illustrated too. The accomplishment of this work not only fills the relevant research blank in China but also is helpful for the improvement of SSD and other works. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15426]  |
| 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 | 周申蕾. 光谱色散平滑技术的研究[D]. 中国科学院上海光学精密机械研究所. 2006. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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