飞秒超短脉冲激光的高平均功率放大及时域、频域整形与压缩新技术研究
文献类型：学位论文
| 作者 | 刘军 |
| 学位类别 | 博士 |
| 答辩日期 | 2007 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 李儒新 |
| 关键词 | 啁啾脉冲放大 载波相位 脉冲压缩 光丝 自准直 |
| 中文摘要 | 最近几年，阿秒脉冲产生以及利用阿秒脉冲研究超快物理现象方面的研究受到国际上激光物理学家与化学学家们的极大关注。自从2001年利用7fs激光脉冲产生的650as的x射线脉冲观测到电子超快运动的突破性进展后，到2006年采用载波相位稳定的5fs激光脉冲已经可以产生脉冲宽度短于200as的单个阿秒脉冲。目前，这一国际前沿科研领域仍然有许多重要物理现象和规律等待着物理学家去发现。已有的理论和实验已经证明利用载波相位稳定的周期量级的高强度飞秒激光脉冲驱动产生高次谐波是获得可重复的单个阿秒脉冲和研究阿秒物理现象的有效方法。因此，获得高精度、高性能和稳定可靠的超短激光脉冲必将进一步推动这一领域的快速发展。 同时，由于在高次谐波产生、飞秒激光微加工、大气中成丝方法进行人工诱雷放电和大气污染监测等研究方向上的重要应用，超短激光脉冲在介质中传输特性方面的研究也极为重要。因此，超短激光脉冲在各种介质中的传输特性方面的研究也成为激光研究领域一大热点。 本论文的工作旨在为阿秒脉冲产生和阿秒物理研究的拓展和深入提供一个先进高效的实验研究平台。论文的主要工作包括超短激光脉冲放大、载波相位稳定、光束指向性的稳定、脉冲对比度提高、脉冲压缩和脉冲传输几个方面。论文工作的主要结果与创新点包括以下几个方面： 1. 在已有的商用激光器基础上，设计搭建了一套钛宝石激光多通放大系统。国内首次获得了放大输出能量>5mJ，脉冲宽度<40fs，重复频率为1kHz的超短激光脉冲。放大器激光的能量转换效率约为30％。 2. 在多通放大器与光栅压缩器之间，我们搭建了一套激光自动准直系统。编写了一套激光光斑模式与稳定性实时监测，以及光束指向性的稳定和自动准直的控制软件。系统可以稳定注入光栅压缩器的激光光斑，从而提高压缩激光脉冲宽度稳定性和系统载波包络位相（CEP）稳定性。稳定的激光光斑也提高了放大器后面的腔外脉冲压缩和高次谐波等物理实验的稳定性和可靠性。同时，此系统还可以实时监测激光光斑模式和稳定性，因此可以在其它很多地方都会有重要应用。 3. 通过使用CEP稳定的振荡器，我们在放大器后面获得了CEP稳定的放大激光脉冲。放大输出激光脉冲的CEP至少可以稳定10秒钟时间。不久将来，通过慢反馈控制CEP稳定振荡器，我们可以获得CEP稳定精度更高的放大激光脉冲。将来，通过差频产生（DFG）和非共线光参量放大（NOPA）的方法，CEP稳定激光脉冲可推进到近红外波段。 4. 实验研究了负啁啾激光脉冲在块状介质中的传输特性。当负啁啾飞秒激光脉冲在正常色散介质中传输时，激光光谱在被压缩变窄的同时激光脉冲也被压窄的新现象。经过介质后的激光光谱和激光脉冲由高斯形状演化为洛伦兹形状。我们还发现了激光光谱红移和脉冲前沿陡峭的现象。同时，我们数值模拟分析了这一传输结果，模拟结果和实验结果很好地符合。最后我们对这一现象给予了解释。 5. 实验研究了气体盒成丝来展宽光谱压缩激光脉冲的新方法。实验中将53fs激光脉冲压缩到15fs。并比较了圆偏振光和线偏振光在气体盒压缩特性。不久的将来利用圆偏振入射我们期望可以获得更高能量短于10fs的压缩输出。 |
| 英文摘要 | In recent years, laser scientists in the world have been engaged in the field of attosecond pulse generation and its applications. After observing the inner-shell electron motion by using a 650as attosecond pulse generated with 7fs driving laser pulses in 2001, scientists obtained an isolated attosecond pulse with pulse duration less than 200as, which was driven by a carrier-envelope phase (CEP) stabilized 5fs laser pulse in 2006. Until now, there are still many potential important mechanism and physical phenomena in this research field to be explored. Many published theoretical and experimental works have proved that it is an effective method to obtain an isolated attosecond pulse and perform some attosecond physics researches by using a CEP stabilized, few-cycle high intense laser pulse to drive the high harmonic generation (HHG). Therefore, intense ultrashort laser pulses with high precision, good performance and nice stability will push the fast progress in the attosecond physics field. At the same time, intense ultrashort laser pulses have broad applications in high harmonic generation, femtosecond laser pulses micro-machining, lightning triggering and the inspection of air pollution based on the filamentation in air and so on. Therefore, it is very important to study the property of the pulse when it propagates in different kinds of optical media. And it had already been one hot research field in laser physics for years. The work of this thesis aims at establishing an efficient and advanced laser system for the generation of attosecond pulse and the study of attosecond physics. Main work in the paper includes pulse amplification, CEP stabilized of amplified pulse, beam self-stabilization, improvement of pulse contrast, propagation and compression of ultrashort pulse. Main results and innovation points in the thesis can be summarized as follows: 1. We developed a cryogenic Ti:sapphire multi-pass amplifier based on a commercial Ti:sapphire laser system. To our knowledge, this is the first time to obtain amplified pulses with pulse energy larger than 5mJ, pulse duration less than 40fs at the repetition rate of 1kHz in the nation. The conversion efficiency of the amplifier is about 30%. 2. We developed a laser beam self-collimation system between the multi-pass amplifier and the grating based pulses compressor. This device can stabilize the beam pointing before the grating based pulses compressor and then improve the stability of the pulse duration and CEP of the amplified pulse. At the same time, it enhances the stability and reliability of the pulse compression and HHG experiment. Moreover, the device can monitor the beam mode and the pointing stability of the laser beam. 3. The CEP stabilized amplified pulses are obtained by using a CEP stabilized femtosecond oscillator. The CEP of the amplified pulse can be stabilized for at least 10s. In the future, we can obtain more stable amplified pulses in CEP with a slow feedback after the amplifier. And CEP stabilized pulses in near infrared region (NIR) can be gained through difference-frequency generation (DFG) and noncollinear optical parametric amplification (NOPA) method. 4. We experimentally studied the nonlinear properties of the negative chirped pulse when it propagates in the normal dispersive medium. The spectrum and the temporal profile are reshaped from Gaussian profile to Lorentzian profile due to strong self-actions. The pulse is self-compressed, instead of broadening, accompanied with the spectral narrowing in linear scale. Steepening of the leading edge of the pulse and spectral red-shift are observed in the experiment. The numerical simulation shows that the results are in agreement with the experimental results. 5. New method of pulse compression is experimentally studied by using the filamentation in a gas-filled cell. A 53fs pulse is compressed to 15fs by using this method and a comparing experiment between circular polarization and linear polarization pulses is performed. We expect to obtain compressed pulse with much higher energy when the incident pulse is circularly polarized. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15418]  |
| 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 | 刘军. 飞秒超短脉冲激光的高平均功率放大及时域、频域整形与压缩新技术研究[D]. 中国科学院上海光学精密机械研究所. 2007. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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