基于深刻蚀光栅的飞秒脉冲压缩装置
文献类型：学位论文
| 作者 | 贾伟 |
| 学位类别 | 博士 |
| 答辩日期 | 2009 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 周常河 |
| 关键词 | 高密度深刻蚀光栅 多台阶反射光栅 飞秒激光脉冲 群速度色散 光学脉冲压缩 频率分辨光学开关法 单发飞秒测量装置 |
| 其他题名 | Femtosecond pulse compressor based on deep-etched gratings |
| 中文摘要 | 在飞秒激光系统中，通常会利用脉冲压缩装置，消除腔内材料色散的影响，一般使用的棱镜对体积庞大且不易调节，而啁啾镜则成本较高。为此，本论文提出了一种基于透射式、高密度、深刻蚀光栅的脉冲压缩装置。该装置具有体积小巧，宽光谱高效率以及激光破坏阈值高等优点，因此具有广阔的应用前景。另外，本论文还介绍了低密度光栅制作工艺的实验研究，并讨论了其在飞秒脉冲激光技术中的应用可行性。基于光栅的分束特点，我们研究了低密度达曼光栅代替菲涅耳棱镜，应用于单发的飞秒脉冲测量装置；考虑到光栅可以引入负色散，我们对光栅进行飞秒脉冲色散补偿和脉冲压缩进行了实验研究。本论文主要内容包括： 1. 低密度闪耀光栅的制作工艺研究。在湿法套刻中，我们对传统的制作过程进行了改进，有效提高了制作质量。本论文以40m四台阶闪耀光栅为例讲述了制作的过程，得到了良好的光栅表面形貌，并且闪耀级次的衍射效率达到了70％以上。相比传统的制作方法，实际效率提高了5％到10％。最后我们对比理论上的衍射效率，分析了实验误差，发现把存在实验误差的光栅进行处理，如把光栅浸泡在HF溶液中可以有效去除对准误差产生的“尖峰”，这将显著的提高其衍射效率，为进一步提高闪耀光栅的衍射效率提供了依据。 2. 基于反射式达曼光栅的单发飞秒脉冲测量装置。阐述了在单发的飞秒测量装置中加入光栅对的实验，即在GRENOUILLE (grating-eliminated no-nonsense observation of ultrafast incident laser light e-fields)中加入了三个达曼光栅，替代原有的菲涅尔棱镜，作为光的分束与合束的器件。在此基础上，我们分别用标准多发FROG装置和基于达曼光栅的单发FROG装置，测量了脉冲在经过色散介质前后的情况，并对实验结果进行了分析比较。 3. 基于多台阶反射光栅的飞秒脉冲压缩装置。反射式光栅对作为一种具有负色散性质的器件被用于飞秒激光脉冲的压缩和展宽，具有无材料色散的优点。为此，本文给出了一种基于多台阶反射光栅的脉冲压缩装置，本装置为倍密度光栅结构，由两个周期分别为40m和20m的四台阶反射式光栅组成，实验得到的光栅衍射效率可以达到70%以上。输入脉冲经过两个光栅的衍射后会按原路返回，从而达到色散补偿的效果。利用此压缩装置，脉冲宽度为66.8fs的输入脉冲压缩至接近傅里叶变换极限脉冲，即46.6fs，由此证明只要多台阶光栅效率足够高，此装置就有可能成为不同于棱镜对进行飞秒脉冲腔内和腔外压缩的另一种途径。 4. 小型化飞秒脉冲压缩器。我们提出了一种小型化的飞秒脉冲压缩器，它可以用于补偿由飞秒激光腔引入的群速度色散。这种压缩器包括两个完全相同的高效率深刻蚀透射式光栅。和通常使用的棱镜对相比，高密度透射式光栅对具有体积小、重量轻等优点。通过理论优化光栅参数，对于800nm波长光波李特洛入射情况下，可以在负一级透射级次上实现98％的衍射效率。这种光栅是通过感应耦合等离子体刻蚀法制作在熔融石英表面的。实验中，我们用这种光栅对将73.9fs的入射激光脉冲压缩到接近傅立叶变换极限的43.2fs。基于深刻蚀光栅的小型化脉冲压缩器将具有很大的应用潜力。 |
| 英文摘要 | In femtosecond laser system, a pulse compression apparatus is usually used to compensate the dispersion introduced by intracavity material. However, the prism pairs are always large and bulky to adjust, and chirped mirrors are too expensive. In this thesis, we propose a pulse compressor based on high-density deep-etched transmission gratings. The device is compact with high damage threshold and high efficiency in wide band of spectrum. It will be highly interesting in femtosecond laser application. In this thesis, the fabrication of low-density gratings is also presented, and these gratings are applied in femtosecond laser technology. Low density Dammann gratings are used as beam splitter in the single shot pulse measurement setup, as low density gratings can usually diffract a laser beam into several equal orders without introducing too much dispersion; With higher density, gratings are used to compensate group velocity dispersion (GVD) that is induced by the intra cavity material dispersion, and the pulses width is compressed. 1. Fabrication of low density blazed gratings. We present the process of fabrication of low density blazed gratings. Some novel improvements have been reported, which results in fabrication of gratings with better quality. In our experiment, we fabricate four phases gratings of 40m period with uniform surface, and the diffraction efficiency of the first order is more than 70%. Compared with traditional method, the efficiency is increased by 5% to 10%. Finally, we compared the efficiency between experimental and theoretical results, and we analyzed the reasons of experimental errors. We found that if tips between two phases introduced by experiment errors can be removed, the efficiency will be greatly increased, which will help us to obtain better gratings with higher diffraction efficiency. 2. A single-shot femtosecond laser measurement device with Dammann gratings. We present a modified GRENOUILLE (grating-eliminated no-nonsense observation of ultrafast incident laser light e-fields) setup, in which the Fresnel biprism is replaced by three Dammann gratings. As a substitute, the gratings can also split the ultrafast pulse beam without any material dispersion. In the experiment, two different pulses are measured by the Dammann GRENOUILLE setup and standard FROG device, respectively. 3. Reflective multilevel gratings based femtosecond laser pulse compressor. Reflective grating pairs are usually used as femtosecond pulse compressors and stretchers because of the advantage of no material dispersion. In this paper, a reflective multilevel gratings based compressor is presented, which is also called double-line-density gratings structure. It contains two four phases reflective gratings with periods of 40m and 20m, respectively, of which the efficiencies are higher than 70%. The input femtosecond pulses go back along the input direction after diffractions of the two gratings, and the positive GVD of the input pulses is compensated. With this compressor, the input pulses of 66.8fs with positive GVD are compressed into Fourier-transform-limited ones of 46.6fs. So it is demonstrated that, with high efficiency, low density reflective grating pair is an alternative approach which is different from prism pair as a compressor for both inside and outside femtosecond laser cavities. 4. Miniature femtosecond pulse compressor. We propose a miniaturized pulse compressor which can be used to compensate the group velocity dispersion (GVD) that is induced from a commercial femtosecond laser cavity. The compressor is composed of two identical high efficient deep-etched transmittive gratings. Compared with prism pairs, high efficient deep-etched transmittive grating pairs will have the advantages of small size and light weight. With optimized groove depth and duty cycle, 98% diffraction efficiency of the -1 transmittive order can be achieved at wavelength of 800 nm under Littrow condition. The deep-etched gratings are fabricated in fused silica by inductively coupled plasma (ICP) etching technology. With a pair of the fabricated gratings, the input positively-chirped femtosecond pulses of 73.9 fs are nicely compressed into the nearly Fourier-transform-limited pulses of 43.2 fs. The miniaturized deep-etched-grating-based pulse compressor should be highly interesting for practical applications. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15268]  |
| 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 | 贾伟. 基于深刻蚀光栅的飞秒脉冲压缩装置[D]. 中国科学院上海光学精密机械研究所. 2009. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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