飞秒激光诱导相变薄膜的光学性质调制
文献类型：学位论文
| 作者 | 雷锴 |
| 学位类别 | 硕士 |
| 答辩日期 | 2016 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 王阳 |
| 关键词 | 相变材料 光学常数 飞秒激光 时间分辨光谱 |
| 其他题名 | Modulation of optical properties of phase-change thin films induced by femtosecond laser pulses |
| 中文摘要 | 按照实际需要来调控材料的光学性质具有非常重要的科学研究和实际应用价值。光学常数是表征材料光学性质的一个十分重要的基础物理参数，它很大程度上决定了器件的光学性能。大部分天然材料的光学常数是一个基本不变的量，而相变材料在外场诱导下随着相态的改变其光学常数有较大变化，这是其在光存储器件中得到应用的重要基础，可以基于此发展新型的可调谐光学器件。 相变材料的相态和光学常数调控主要采用热退火、连续激光初始化或者纳秒激光脉冲诱导的方法，速度慢，可控性较差。由于超短激光脉冲（如飞秒和皮秒激光脉冲）与物质相互作用时，能够很大程度上抑制材料中的热扩散，因此适于精确控制相变材料的相变过程和程度。研究表明通过飞秒脉冲重复照射相变薄膜的同一区域能够实现材料反射率的连续调控，但对于更具基础物理意义的光学常数调制则鲜有报道。 本文主要通过改变飞秒激光脉冲数量密度和能量密度两种方法实现了Sb70Te30相变薄膜在晶态和非晶态之间有效折射率的准连续调制。基于相变薄膜可调控的光学常数，设计了多层膜光学显示单元，通过数值模拟分析了相变层折射率及膜层结构在颜色精细调控中的作用。结合时间分辨光谱测量、双温模型数值计算、薄膜表面分析等讨论了飞秒激光诱导相变薄膜光学常数精密调控的机制。研究结果对深入理解极端非平衡条件下的相变机制，以及光学性能可精密调控相变器件（如多阶存储、显示和逻辑器件等）的设计和应用具有重要参考价值。 |
| 英文摘要 | Controlling optical properties of materials on-demand is an important issue in scientific researches and practical applications. Optical constants are basic physical parameters to characterize the optical properties of materials and determine the performance of optical devices. For most natural materials, their optical constants are constant values. While for phase-change materials (PCMs), their optical constants are dependent on their phases and can be changed under external fields, which is the basis of their applications in optical storage devices. Furthermore, novel tunable optical devices can be developed based on it. The modulation of phases and optical constants of PCMs are often realized by thermal annealing, initialization with continuous-wave laser, or nanosecond laser pulse induction, which are time-consuming and have poor controllability. The phase transition process and crystallization extent of PCMs can be controlled precisely by ultrashort laser pulses due to the suppressed thermal-diffusion during the ultrafast laser-material interaction. Some studies show that the reflectivity of phase change thin films can be continuously changed by successive femtosecond laser pulses irradiation on the same area. However, there are little studies focused on the refractive index modulation of phase change thin films, which has more fundamental physical meaning. In this dissertation, the phase states and effective refractive indexes of Sb70Te30 phase-change thin films were modulated quasi-continuously between the crystalline state and the amorphous state by controlling the laser pulse number density or laser pulse power. Stacked film structures were designed for adjustable and fine color display based on the controllable optical constants of PCMs. The modulation mechanism of optical constants of phase change thin films induced by femtosecond laser pulses was discussed comprehensively by time-resolved spectroscopy, two-temperature model calculation and surface analysis. These results will be helpful for the deeper understanding of the phase change mechanism under extreme non-equilibrium conditions and design and application of configurable optical devices based on the controllable optical performances of PCMs. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16957]  |
| 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 | 雷锴. 飞秒激光诱导相变薄膜的光学性质调制[D]. 中国科学院上海光学精密机械研究所. 2016. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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