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题名	高反膜内损伤相关的超快动力学研究
作者	袁伟
文献子类	硕士
导师	杜鹃
关键词	超快激光 Ultrafast laser 泵浦探测技术 Pump-probe technology 高反膜 High reflectivity optical thin film
其他题名	Study on the damage related ultrafast dynamics in high reflectivity optical thin films
英文摘要	光学薄膜是激光系统中不可缺少的基本元件，也是超强超短激光系统中最薄弱的环节之一，其激光损伤问题一直是限制超强超短激光系统向高能量、高功率方向发展的“瓶颈”。不同于纳秒脉冲，飞秒激光引起的材料损伤过程具有较强的本征损伤特性，作为飞秒损伤诱因的各种电子态无法显微观测。因此，开展介质材料损伤相关的超快动力学研究，了解超强超短脉冲激光作用下光学材料、元件的激光破坏相关动力学过程，对于阐释超强超短激光作用下薄膜材料及元件的损伤机理，以及探索改善薄膜材料及元件抗超强超短激光脉冲损伤能力的途径，具有非常重要的实际意义。 本文采用不同波长的飞秒脉冲激光系统，通过对泵浦-探测技术的改进，研究了Al2O3/SiO2高反膜及Au高反膜内损伤相关的动力学过程。通过对这些高反膜内部载流子运动过程进行时间分辨和光谱分辨的进一步分析，深入了解了飞秒激光作用下介质高反膜与金属高反膜的损伤过程。具体工作与取得的研究成果如下： 1.对泵浦-探测实验平台进行了改进，通过引入色散补偿器件调整输出脉宽，分别实现了中心波长为400nm以及800nm的宽波段超快激光测试能力，将以往的单波长泵浦探测实验扩展为宽光谱泵浦探测实验，有助于获取材料内部与损伤相关的更多缺陷态的信息。 2.通过泵浦探测实验，研究了中间能量缺陷态的存在对于光学薄膜材料光学性能及其激光损伤阈值的影响。首先，采用400nm的飞秒激光，观察到了Al2O3/SiO2高反膜内与激光诱导损伤密切相关的缺陷态的存在，并通过对反射率随时间的变化进行相应的频域分析，对该中间缺陷态进行了精确的能带定位。在此基础上，进一步研究了激光预处理对该中间缺陷态的影响，得到了预处理会导致缺陷态密度增加从而降低薄膜损伤阈值的结论。 3.采用800nm的飞秒激光，对Au高反膜内的载流子超快动力学过程进行了研究。我们分别采用不同能量的激发脉冲，得到了相应的金膜反射率在时域和频域的演化信息。通过进一步的分析，首次发现在飞秒激光的作用下，金膜内部电子会通过双光子吸收等非线性吸收方式在能级之间产生跃迁。同时，我们利用双温模型解释了飞秒激光与材料相互作用的过程中电子以及晶格的热动力学过程，并模拟了激光与材料相互作用后电子与晶格温度随时间的变化过程。; The optical thin film is an indispensable component in laser system, it is the weakest link is the ultrashort and ultrahigh laser system too. The laser damage problem of optical thin films has been the bottleneck to the development of high energy and high power direction of ultrashort laser system. Femtosecond laser induced material damage process has strong intrinsic damage characteristics, which is different from nanosecond laser pulses, however, various electronic states which leads to femtosecond damage can not be detected by microscope. Therefore, carrying out the damage related ultrafast dynamics in medium material, and understanding the ultrafast laser damage related dynamics of optical materials have great importance to explain the damage mechanism between thin film materials and ultrashort laser pulses, it is also important to improve the laser system performance. We exploited ultrafast femtosecond laser system with different wavelengths. By improving the pump-probe technology, we researched the interaction mechanism between the ultrafast femtosecond laser pulse and Al2O3/SiO2 high reflectivity optical thin films, as well as Au high reflectivity optical thin films, and made some progress. Through the further analysis of the time resolution and the spectral resolution of the carrier motion in these highly reflective films,the damage process of the medium high reverse films and the high metal reverse films under femtosecond laser irradiation is further studied .Specific work and progress are as follows: 1.The pump probe experiment was improved, we used dispersion compensation device to adjust output pulse width and broadened the spectrum to build 400nm and 800nm ultrafast ultraviolet femtosecond pulse laser system, and expanded the single pulse pump probe experiment to wide spectrum pump probe experiment to get more information about defects in the material interior. 2.By pump-probe experiment, The effects of intermediate energy defect states on optical properties and laser induced damage threshold of optical thin films were investigated. Firstly ,we detected the defect state which is related to laser induced damage in Al2O3/SiO2 high reverse film by using 400nm femtosecond pulse laser. The defect state is located precisely by variation of reflectivity with time. Based on this, the effect of laser pretreatment on the intermediate defect states was further studied, and draw the conclusion that the laser pretreatment would reduce the film damage threshold. 3.In the study of interaction between 800nm femtosecond laser and Au high reflectivity film. We used several pump pulse with different energy, and get the evolution information of gold film reflectivity in time domain and frequency domain. By further analysis, we observed two-photon absorption under the femtosecond in gold film for the first time. We used two temperature model(TTM) to calculated the electron and lattice temperature after the pump pulse excitation as well.
学科主题	光学工程
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/30961]
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	袁伟. 高反膜内损伤相关的超快动力学研究[D].

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