基于电磁诱导透明的激光器稳频技术研究
文献类型：学位论文
| 作者 | 应康 |
| 学位类别 | 博士 |
| 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 | 瞿荣辉 |
| 关键词 | 电磁诱导透明 半导体激光器 色散 稳频 |
| 其他题名 | Study on Laser Frequency Stabilization Technology via Electromagnetically Induced Transparency |
| 中文摘要 | 高精度、可靠性强的激光器频率控制技术在高精度干涉仪、高分辨率激光光谱学、激光原子冷却与原子钟、相干激光雷达、相干激光通信、光纤水听器、分布式光纤传感等前沿基础科学和高技术领域有着重要和广泛的应用需求。例如在冷原子钟领域，它需要一套具有窄线宽、高频率稳定性的光源系统，尤其是激光器对之间的相对频率差必须严格等于原子的能级间距。针对这些需求，本论文旨在研究一种基于电磁诱导透明现象（EIT）的半导体激光器的相对频率稳定技术。所采用的方法是通过探测场激光器和控制场激光器在原子介质内部的多光场干涉形成双暗态EIT透明峰，并通过PID闭环反馈回路，将激光器的频率锁定在极窄的EIT透明峰处，由于EIT的透明峰表征了不同激光场之间有着固定的相对频率差，这样就实现了激光器对之间的相对频率稳定；并且由于双暗态EIT透明峰有着大的色散和宽的调谐范围，所以我们可以实现在较长的时间内提高激光器的相对频率稳定精度。 因此，本论文重点进行了热原子的EIT现象实验研究和基于EIT的激光器相对频率稳定技术研究，主要内容如下： 1、详细论述了EIT的基本原理和理论描述。介绍了EIT现象的半经典描述，从光与物质相互作用的半经典理论出发推导出EIT现象；重点描述在四能级双暗态原子系统中，暗态间的相互作用产生的光场极化率实部和虚部的变化；此外，我们还介绍了腔内原子系统对谐振腔透射谱调制的理论叙述。 2、搭建热原子量子光学实验平台，深入进行热原子EIT现象实验研究。综合考虑实验设备，量子效率，能级偶极距等因素后，选择铷原子（Rb）的D2线作为工作能级，输出波长在780 nm的外腔半导体激光器作为光源激光器。重点在实验上研究了V-型和Tripod -型（双Lambda-型）能级构型的EIT现象，详细探究了原子温度、光强、频率失谐等实验参数对EIT现象的影响。在实验上成功观察到了V-型的多重EIT透明峰和Tripod-型的极窄EIT透明窗口，得到了可以用于激光器频率稳定的高精度的频率参考信号。 3、在工作二获得了Tripod-型极窄EIT透明峰的基础上，通过实验和理论详细研究了实验参数对这个极窄EIT透明峰宽度的影响，在选取合适实验参数的情况下，得到了宽度接近激光器线宽的窄EIT透明窗口（590 kHz）。通过PID闭环反馈回路对半导体激光器的外腔电压和驱动电流进行反馈控制，成功锁定了探测场激光器和其中一个控制场激光器的相对频率波动，在半小时的时间内，将激光器的相对频率波动控制在60 kHz，小于单个激光器的线宽。 本论文的另外一部分工作是基于原子系统的线性和非线性色散对光学谐振腔透射谱调制的实验研究。在实验上，通过V-型和Tripod-型腔内EIT系统，成功地实现了谐振腔透射峰线宽的压窄；更进一步地，通过实验和理论研究，我们发现在N-型原子系统内，线性和非线性色散的符号可以通过两个控制场的相对强度进行调制，因此在一个非常宽的腔场强度的范围内，白光腔条件都可以得到满足。在合适的实验参数下，我们在几十微瓦至几十毫瓦的腔场强度下，都实现了白光腔。我们的研究结果有望在引力波探测，光波整形，非线性光谱等研究获得广泛应用。 |
| 英文摘要 | High-resolution, reliable laser frequency stabilization technology has applications in many frontier areas such as high-resolution interferometer, high-resolution interferometer spectrum, atomic clocks, coherent lidar, coherent optical communication, fiber optic hydrophone, distributed optical fiber sensing, et al. In some areas such as atomic clocks, it needs a laser system with the characteristics of narrow-linewidth and high frequency stability, especially the frequency difference between the lasers must be controlled to high precision. According to these application requirements, this thesis aims to do a research on laser frequency stabilization technology via electromagnetically induced transparency (EIT). The method is that firstly establishing the double dark state EIT transmittance peak by the coherence between the probe and control lasers in the atomic medium; then, the lasers’ frequency is locked to the EIT transmittance peak via the PID feedback channel. As the frequency difference between the different lasers’ field corresponds to the atomic level splitting in the EIT transmittance peak, the relative frequency between the probe and control laser is locked by this way. Moreover, the large dispersion and wide tuning range exist in the double dark states EIT transmittance peak, the high lasers’ relative frequency stability in a long time can be expected. Therefore, this thesis focuses on the experimental study of the hot atomic EIT and the technology of laser’s relative frequency locking, and the main work is summarized as following: 1. The fundamental theory of EIT has been stated in detail. The semiclassical theory of EIT is introduced, that is to say, EIT can follow from the semiclassical theory of the interaction between optics and matters. We describe the tendency of dispersion and transmittance induced by the coherence between the two dark states in the Tripod-type atomic system. Lastly, the theory of modulation of cavity transmittance spectrum via intracavity atomic system has been stated. 2. The hot atomic quantum optical setup up is established and the experimental study on EIT of hot atomic medium is done. Considering some experimental parameters such as quantum efficiency, dipole moment of atomic levels, the D2 line of Rb is used as our experimental levels and external cavity diode laser working at 780 nm is used as our laser source. The V-type and Tripod-type EIT is studied experimental. The influence of some experimental parameters such as atomic temperature, amplitude, frequency detuning on the EIT signal is studied in detail. The multi-EIT peaks in V-type system and ultranarrow EIT peak in Tripod-type system are observed experimentally which can be used in laser frequency stabilization. 3. In order to characterize the Tripod-type EIT signal, its dependence on the experimental parameters, such as the coupling fields’ power and detuning, is investigated experimentally and theoretically. The ultranarrow EIT peak with a linewidth of 590 kHz is obtained under appropriate experimental parameters. Under the PID feedback channel of laser’s external cavity voltage and drive current, the relative frequency of probe laser and control laser is locked to the ultranarrow EIT peak. The fluctuation of relative frequency is 60 kHz@2000s, which is less than the linewidth of laser. 4. Another part of this thesis is the experimental study on the modulation of optical cavity transmittance spectrum via the atomic linear and linear dispersion. The cavity linewidth is narrowed via V-type and Tripod-type EIT system experimentally. According to the theoretical and experimental study, the sign of linear and nonlinear dispersion can be modulated via adjusting the relative intensity of two control fields in an N-type atomic system. As a result, the condition of white light cavity can be satisfied in a wide range of cavity field’s intensity. Under appropriate experimental parameters, we establish the white light cavity in the cavity field intensity from a few μW to dozens of mW. Our research result has potential application in the areas such as gravitation wave detectors, pulse shaping, nonlinear spectroscopy, etc. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/15906]  |
| 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 | 应康. 基于电磁诱导透明的激光器稳频技术研究[D]. 中国科学院上海光学精密机械研究所. 2015. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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