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题名	空间冷原子钟新型光源设计
作者	张远涛
学位类别	硕士
答辩日期	2015
授予单位	中国科学院上海光学精密机械研究所
导师	吕德胜
关键词	非线性光学 热效应 光谱学 饱和吸收 塞曼效应
其他题名	The Design of a New Type Laser Source for the Space Atomic Clock
中文摘要	激光器是冷原子钟的重要组成部分，为空间冷原子钟的激光冷却、原子布局数探测等工作步骤提供必要的光源。本论文介绍了一种新型的基于倍频的激光光源方案，能更加容易地解决空间冷原子钟对激光功率、线宽和环境适应性的要求，该论文同时研究了环境磁场变化对激光稳频饱和吸收光谱的影响。 论文的第一部分，介绍了全光纤的倍频激光光源方案，该方案是通过PPLN波导晶体模块倍频得到780 nm激光，由于使用的是全光纤光路，光学系统可以更紧凑和牢固。作为实验的准备，在理论上计算了倍频光路中各个参数，重点介绍了倍频，通过有限元仿真的方式对晶体的热效应进行了研究，仿真结果表明，当采用合适的晶体尺寸时，会降低热效应带来的影响，该结果对以后激光光源的实验有指导意义。 饱和吸收是稳频的基础，其光路也是冷钟中激光光源的一个重要部分，本文详细研究了不同泵浦光与探测光功率比值对饱和吸收光谱的影响，同时还观察了分别用PBS的透射光和反射光作为泵浦光时，对饱和吸收的影响。结果表明，透射光作为泵浦光时，饱和吸收现象要优于使用反射光的情况，光配比在1：0.04附近，会有比较好的饱和吸收线型。 此外研究了在弱磁场下，不同偏振的泵浦光和探测光作用时，饱和吸收光谱的变化。发现当探测光为圆偏振光时，在平行于光传播方向的磁场作用下，交叉峰会随着磁场的增强而减弱，与此同时，F_g=2到F_e=3的共振峰附近出现一个增强吸收峰；当探测光和泵浦光为线偏振光，磁场平行于光传播方向时，在磁场大小为0.9-1 mT时，F_g=2到F_e=3的共振峰达到最大。 通过本文的研究，得到了一种新型的激光器，能够满足其在空间应用方面的需求。同时，饱和吸收的相关实验结果对激光器的稳频有一定的指导意义。
英文摘要	Laser is one of the most important components of a cold atomic clock. It provides the appropriate laser source for the laser cooling and trapping and atomic states population detection when the space cold atomic clock is working. This thesis presents a novel strategy to produce a 780 nm laser by using frequency doubling. This strategy can easily meet the laser power and line-width requirement of the space cold atomic clock. On the other hand, this thesis investigated the influence of environmental magnetic field on saturated absorption spectrum. At the first part, a frequency doubling laser source scheme was introduced. In this scheme, full fiber light path was adopted and 780 nm laser was obtained by a PPLN waveguide, so it can be very compact and robust. As a preparing job, optimal optical parameters of the scheme was calculated theoretically. Afterwards, more attentions were paid to introduce the effects of thermal on the frequency doubling. Finite-element method was used to analyze the thermal effects. It is demonstrated that the performance of the PPLN crystal on frequency doubling can be improved by choosing the appropriate crystal size. This conclusion is instructive and meaningful to the farther experiment of new laser source. As the fundamental of frequency stability, saturated absorption spectrum was studied in detail. It’s also the part of laser source which is used in the atomic clock. The spectra line was observed under different ratios of pumping and probing laser. In addition, the influence of pumping and probing polarization on the line strength was also discussed. The result indicated that the pumping laser passed PBS will be better than the reflected one for the saturated absorption experiment. Besides, optimal spectra will be achieved when the ratio is around 1:0.04. Furthermore, the variation of saturated absorption spectra line caused by weak magnetic field was studied in detail. Different kinds of polarization of pumping and probing was used in this experiment. As a result, in the case of circle-polarized pumping and probing laser, when the magnetic field direction was as the same as laser propagation, crossover peak was decreased as the magnetic field amplitude becoming stronger. Moreover, an enhanced absorption peak was appeared near the resonance peak of F_g=2 to F_e=3 under this situation. Otherwise, the saturated peak will became the strongest when the magnetic amplitude is about 1 mT, if the field direction is parallel to the laser propagation. This thesis obtained a new scheme of laser source, which can meet the requirement of space application. What’s more, the relative result of saturated absorption will be reference for the laser frequency stability.
语种	中文
内容类型	学位论文
源URL	[http://ir.siom.ac.cn/handle/181231/16936]
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	张远涛. 空间冷原子钟新型光源设计[D]. 中国科学院上海光学精密机械研究所. 2015.

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