飞秒激光脉冲在透明介质中的非线性传输与控制研究
文献类型：学位论文
| 作者 | 季忠刚 |
| 学位类别 | 博士 |
| 答辩日期 | 2010 |
| 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 | 飞秒激光，成丝，等离子体通道，锥形辐射 |
| 其他题名 | Study on the Nolinear Propagation and its Control of Femtosecond Laser Pulses in Transparent Media |
| 中文摘要 | 近年来，超短激光脉冲在空气等透明介质中的成丝传输引起了极大的研究兴趣，并逐渐形成了一个极为活跃的研究领域。这种传输过程具有许多独特的性质，例如光丝中的功率密度锁定，产生长距离稳定的等离子体通道，可以保持一定的功率密度将能量传输到很远的距离等。因而在诸如周期量级激光科学、遥感探测、气候学等多个领域展现出了广阔的应用前景。 本论文主要研究了飞秒激光脉冲在空气以及玻璃等介质中传输时一些重要参数的诊断及相关特性，在多个方面研究了如何有效的控制激光脉冲在空气中的成丝传输，并在激光天线、THz辐射源等应用方面作了初步研究。主要研究结果如下： 1、利用不同的实验方法对飞秒激光脉冲在空气中成丝传输的阈值、光丝直径、光丝长度、等离子体中的电子密度等作了系统研究。研究发现了光丝的直径随透镜焦距及脉冲能量的变化，证实了飞秒激光脉冲的无电离自引导传输机制。 2、利用PW激光系统研究了大功率飞秒激光脉冲在空气中的传输特性。发现大功率激光传输时会因多丝的影响而引起的光束整形，证实了在更高的功率条件下超短激光脉冲成丝传输的功率密度锁定效应。 3、研究了飞秒激光脉冲在空气中形成等离子体通道的电阻特性及弛豫寿命。通过提高激光能量可以降低等离子体通道电阻。用外加高压、引入多脉冲序列等方案延长了等离子体通道寿命，并在激光等离子体通道上成功加载与接收无线电信号。在已取得的实验结果中，最长可以把等离子体通道的寿命从20纳秒延长到300纳秒。 4、采用四波混频和加电压场两种方法研究激光等离子体产生THz辐射的规律。采用加电压的方法可以提高激光等离子体辐射THz脉冲的功率。 5、系统研究了飞秒激光脉冲在玻璃中产生锥形辐射的各种影响因素。实验研究了锥形辐射角与激光功率、脉宽、谱宽、透镜焦距、光丝长度等参数的关系。实验还观测到了红移波段的锥形辐射，我们的实验结果可以用X波模型很好的再现。 |
| 英文摘要 | In recent years, the filamentation of ultrashort intense laser pulses generated in gas has aroused a great interest and become a field of intense research activities. Its unique properties such as efficient power delivery to a long distance without intensity decrease, intensity clamping, and the creation of a stable long plasma channel, etc, have given birth to many potential applications, including few-cycle laser science, remote sensing, climatology, etc. The study on the nonlinear propagation of femtosecond laser pulses in air and glass, including the measurements on some important parameters and properties, the control of the laser propagation in air in various ways, and the applications such as the laser antenna, THz source, etc, are the main subject of this Ph. D dissertation, the main results are listed as follows: 1. The threshold power, diameter, length of the fs laser pulses fiamentation in air, and the electron density of the plasma channel have been systemically investigated by different techniques. The transverse evolution of plasma channel in air with different pulses energies and foci was found. The investigation confirmed the self-channel propagation regime without ionization. 2．The propagation property of ultra high power fs laser pulses was investigated with the PW laser system. The beam quality of the ultra high power laser could be improved during the propagation when multi-filaments occurred. Even if the laser power increased by 100 times, the peak intensity in the filamentation zone increased only a little, which confirmed the intensity clamping effect under ultrahigh laser power conditions. 3. The electric conductive property and the lifetime of the plasma channel generated by fs laser pulses were investigated. The resistance of the plasma channel was reduced and its lifetime was prolonged by different ways, such as adding high voltage and using pulses sequences. The lifetime had been prolonged from 20 ns to 300 ns. The radio signals have been loaded on the laser plasma channel and then received at different distances, wich proved the feasibility of laser antenna. 4. The THz emission characteristics of the laser plasma channel have been experimentally investigated by two methods: four-wave rectification and adding electric field. The THz pulse energy was increased through adding an extral electric field. 5. Conical emission in glass has been investigated experimentally by laser pulses with different laser power, pulse durations, spectral bandwidths, and focus conditions. Red-shift conical emission has also been observed. The calculation result indicated the validity of X-wave mode. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15297]  |
| 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 | 季忠刚. 飞秒激光脉冲在透明介质中的非线性传输与控制研究[D]. 中国科学院上海光学精密机械研究所. 2010. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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