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题名	中红外超短激光脉冲放大和传输研究
作者	黎文开
文献子类	博士
导师	冷雨欣
关键词	中红外 mid-infrared 超短激光脉冲 ultrashort laser pulse 光学参量放大 optical parametric amplification 自压缩 self- compression 非线性折射 nonlinear refraction
其他题名	Research on amplification and propagation of mid-infrared ultrashort laser pulse
英文摘要	中红外超短激光脉冲，这里主要是指工作波长在1.5~10?m的超短激光脉冲，具有广泛的应用需求，例如：中红外波段包含了多种大气分子的振动吸收特征光谱，超短的中红外超短激光脉冲能用来进行分子化学过程动态检测，气体成分高精度定量分析以及基于呼吸气体分析的人体健康状况无损诊断；由于水分子的吸收峰也处于中红外波段，因此中红外激光也被广泛应用于医疗；另外，中红外超短强激光由于与材料作用时具有高的有质动力势，所以可以用于驱动产生更短波长的高次谐波，推动阿秒科学的发展等。因此，开展中红外超短激光脉冲放大和传输研究在基础研究和前沿应用等方面具有重要应用价值，也是当前国际研究热点之一。 本论文主要开展针对中红外超短激光脉冲的光学参量放大过程和传输过程的研究，包括中红外超短激光脉冲脉宽测量，中红外超短激光脉冲在固体中自压缩，基于中红外超短激光脉冲的Z-scan等。本论文取得的主要创新成果和研究进展包括： 1． 对光学参量放大中的像散传递过程开展深入研究。通过模拟和实验研究了在光学参量放大过程中信号光、闲置光和泵浦光之间的像散传递过程，发现放大过程中泵浦光的像散会传递给闲置光，但是不会影响信号光，该像散传递过程并不会受到信号光的偏振态以及泵浦光强变化的影响。 2． 基于三波耦合方程，对光学参量放大过程中信号光脉冲的时间平滑特性开展了模拟研究。发现光学参量放大过程中的平滑能力主要来源于增益饱和以及时间走离两种机制，但是两种的作用效果却不相同。其中增益饱和仅能平滑激光脉冲时间强度上的调制而不能平滑相位，而时间走离机制可以同时平滑激光脉冲强度和相位的调制。进一步研究发现宽带光学参量放大和走离平滑是可以同时实现的，并给出相应的数学关系来估计对应于某走离条件的可以平滑的最大调制周期。 3． 开展中红外超短激光脉冲在固体材料中的自压缩过程研究，并设计了2~10?m可调谐单周期的超短激光脉冲源。通过对不同激光波长，选择合适的反常色散固体材料，进一步优化固体材料厚度等，可以实现2~10?m范围内调谐的单光周期输出。 4． 基于发展的中红外超短激光脉冲源，开展了中红外Z-scan技术研究，并测量了AGS和ZGP晶体的非线性折射率，如在4650nm波长时AGS的O光非线性折射率为1.5E-14 cm2/W。测量中发现在这两种晶体中不同的偏振态的非线性折射率的差别并不大，同时AGS的测量结果与按照直接带隙材料计算的理论值基本一致。 5． 发展了中红外超短激光脉冲宽度测量的SHG-FROG技术，测量了中心波长为4238nm的中红外超短激光脉冲，同时利用PCGPA算法迭代恢复了该待测脉冲的电场强度和相位，脉冲宽度测量为123fs。; The mid-infrared ultrashort laser pulse, including 2~10?m, has a widely applications. Such as, the mid-infrared includes many absorption lines of the gas molecules, so the mid-infrared ultrashort pulse can be used to observe the dynamic process of the chemical experiment, high-resolution quantitative analysis of the gas and non-destructive diagnosis of the health by the analysis of the respiratory gases. Because the mid-infrared includes the absorption peaks of the water, the mid-infrared laser can be used for the surgery. In addition, the mid-infrared ultrashort laser has the high ponderomotive potential in the reaction of the material, so it can be used to produce the short wavelength of the high harmonic wave, and will promote the development of attosecond science. Therefore, development of the mid-infrared ultrashort laser has become one of the hot international research works. The thesis has investigated the amplification and propagation of the mid-infrared ultrashort laser pulse, including the measurements of the mid-infrared ultrashort pulse, the self-compression of the mid-infrared laser pulse in bulk, the Z-scan based on mid-infrared laser pulse. The major innovations and progresses in this thesis are listed as below: 1. The astigmatism transfer phenomena in the optical parametric amplification has been deeply analyzed. In the thesis, the astigmatism transfer relationships between the coupled waves during the parametric amplification have been numerically and experimentally investigated, the results show that the astigmatism of the pump beam can transfer to idler beams but cannot transfer to signal beam, the polarization of the incident beams and the energy of the pump will not affect the astigmatism transfer process. 2. In the thesis, the smoothing effect in the parametric amplification has been numerically analyzed based on the coupled three-wave equations, the analysis show that the smoothing process is invoked by two mechanisms, including gain saturation and temporal walk-off, but these two mechanisms have distinct effect. The gain saturation mechanism can just smooth the temporal intensity, but the walk-off mechanism can smooth both the temporal intensity and phase. In addition, the gain bandwidth corresponding to distinct walk-off has been calculated, the result illustrates that the broad bandwidth parametric amplification and walk-off smoothing can be achieved simultaneously. The equations to estimate the maximal smoothable cycle have been demonstrated in the thesis. 3. The self-compression of the mid-infrared ultrashort laser pulse in solid material has been investigated, and a widely tunable (2~10?m) single-cycle source has been designed. By choosing the proper materials and optimizing the thicknesses, the single-cycle pulses tunable in the range of 2~10?m has been realized. 4. Based on the mid-infrared ultrashort laser, the Z-scan technology has been investigated, and the nonlinear refractive indices of AGS and ZGP have been measured. Such as, the nonlinear refractive index of AGS at 4650nm of O polarization is 1.5E-14 cm2/W. The measured results show that the distinction of the different polarization of the incident pulse in these crystals is small, meanwhile, the measured value of the AGS agrees with the calculated value based on dispersion theory of the direct gap material. 5. The SHG-FROG technology for the measurement of the duration of mid-infrared ultrashort laser pulse has been developed, based on the device a 4238nm ultrashort pulse has been measured, and the intensity and phase of the pulse have been retrieved according to the PCGPA algorithm. The retrieved duration is 123fs.
学科主题	光学
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/30919]
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	黎文开. 中红外超短激光脉冲放大和传输研究[D].

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