用于汞原子光晶格钟的钛宝石激光器注入锁定技术的研究
文献类型：学位论文
| 作者 | 李文杰 |
| 文献子类 | 硕士 |
| 导师 | 徐震 |
| 关键词 | 光晶格钟 Optical lattice clock 注入锁定 injection-locking 钛宝石激光器 Ti: sapphire laser ? |
| 其他题名 | Research on the Ti: sapphire injection locking technology for mercury optical lattice clock |
| 英文摘要 | 近年来，光晶格钟取得了巨大的发展，稳定度和不确定达到10-18量级。但是黑体辐射限制光晶格钟不确定度进一步提高。汞原子由于受黑体辐射的影响较小，成为热门的频标候选元素。原子能级在光场中会产生光频移，幸运的是，在魔术波长的光场中，原子上下能级的频移大小相等，从而消除了钟频跃迁的光频移。汞原子钟频的魔术波长为362.5 nm，位于紫外波段，难以直接获得，一般用高功率、窄线宽的725 nm激光倍频来得到。另外，由于汞原子的极化率很小，要想得到足够的晶格深度将汞原子束缚在晶格内不发生隧穿需要数十瓦的光功率，在实验上，一般利用几百毫瓦、窄线宽的362.5 nm激光进行腔增益得到。本论文拟用钛宝石激光器注入锁定技术得到高功率（瓦量级）、窄线宽（几百kHz）的725 nm激光输出。相比于钛宝石激光器，注入锁定的钛宝石环形腔内不用插入双折射滤光片和标准具等选频元件，腔内损耗小，因而具有更高的泵浦效率。而输出激光的线宽则取决于种子激光的线宽，因此注入锁定钛宝石激光器可以具有更窄的线宽。本人在硕士期间的工作主要是围绕钛宝石注入锁定技术展开的。 首先，自制了725 nm外腔反馈半导体激光器（ECDL），作为注入锁定钛宝石激光器的种子激光器。该种子激光器的输出功率最大为45 mW，波长调谐范围为724-727 nm，无跳模可调谐范围为1.7 GHz。种子激光耦合到保偏光纤，光纤输出功率约为20 mW，耦合效率为70%。 然后，利用ABCD矩阵计算了钛宝石环形腔的各项参数。根据环形腔的稳腔范围、腔模，确定了环形腔的腔型。根据高斯光束的传输原理，设计了种子光和泵浦光与环形腔的模式匹配方案。用有限元方法模拟了钛宝石晶体的热透镜效应，并设计了晶体的通水热沉。 最后，实验上搭建了钛宝石环形腔，得到了环形腔的TEM00模信号和PDH误差信号，并在没有泵浦光的条件下，把环形腔的腔模锁定在种子光频率上。调节了泵浦光路，观察到了荧光信号。 本文初步实现的钛宝石激光器注入锁定技术，为今后产生大功率的725 nm激光并实现倍频积累了很多关键技术，未来可用于汞原子光晶格钟的研究。; Recently, great progress has been made on optical lattice clock, its stability and uncertainty reached a 10-18 level. However, blackbody radiation limits the development of optical lattice clock. Due to its low sensitivity to blackbody radiation, mercury (Hg) has become a good candidate of frequency standard. Light shift will occurs when atoms were trapped in light field. Fortunately, at the light field of magic wavelength, the shift of clock transition can be cancelled because of the same shift of the ground state and excite state. The magic wavelength of Hg clock frequency is 362.5 nm. As it located in the ultraviolet band which cannot be directly obtained, it is generally frequency doubled from a high power and narrow line width 725 nm laser. Additionally, due to its low polarizability, ten watts of laser power is required to deeply trap the atoms in the lattice without tunneling. Typically it is cavity enhanced with few hundreds mW, 362.5 nm laser. With the Ti:sapphire injection locking technology, we plan to generate a high power (Watt level), narrow line width (few hundreds of kHz) 725 nm laser output in this thesis. Compared with the commercial Ti:sapphire laser, we don’t need to insert birefringent filter and etalon to select the laser frequency in the Ti:sapphire ring cavity with injection locking technique. The cavity loss is smaller, so it is higher efficiency. And the line width of the output laser is just dependent on the line width of the seed laser, so it can give narrower line width with injection locking technology. The main work of my research is about the study of Ti:sapphire injection locking technology at 725 nm in this thesis. Firstly, a 725 nm external-cavity diode laser (ECDL) is home made as the seed laser of the injection locking. The output power is up to 45 mW, the tunings wavelength range is 724-727 nm, and the hop-free range is 1.7 GHz. The seed laser is coupled to a polarization maintaining fiber. The output power of the optical fiber is about 20 mW, and the coupling efficiency is 70%. Secondly, the parameters of the Ti:sapphire ring cavity was calculated by the ABCD matrix method. The cavity configuration is determined by the stable condition and the waists of the ring cavity. The mode matching strategy between the seed beam (pump beam) and the ring cavity was designed according to the propagation theory of Gaussian beam. The thermal lens effect of the Ti:sapphire crystal was simulated by finite element method, and the water chilled heat sink was designed for the Ti:sapphire crystal. Finally, the Ti:sapphire ring cavity was biult. The signal of TEM00 mode and the PDH error signal of the ring resonator were observed, and the ring cavity was locked on the seed laser without the pump laser. Adjusting the pump laser on the Ti:sapphire crystal, the fluorescence was observed. In this paper, the Ti:sapphire injection locking technology was studied. Some key techniques are accumulated for the generation of high-power 725 nm laser, frequency doubling and the further application on the research of mercury atomic lattice clock. |
| 学科主题 | 光学工程 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/30989]  |
| 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 | 李文杰. 用于汞原子光晶格钟的钛宝石激光器注入锁定技术的研究[D]. |
入库方式： OAI收割
来源：上海光学精密机械研究所
浏览0
下载0
收藏0
其他版本
除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。