【作者】 张艳峰；

【导师】 张天才；

【作者基本信息】 山西大学 ， 光学， 2012， 硕士

【摘要】 位相锁定、频差在数GHz量级且可以精确调节的激光在受激拉曼光谱、受激拉曼冷却、原子的相干布居俘获、量子态的制备等量子调控研究中具有重要的作用,近年来得到了人们广泛的关注。人们发明了一系列的方法来产生这种光源。其中比较常用的有：将经过声光或者电光调制器调制后的激光注入锁定到从激光器、直接对半导体激光器进行电流调制然后将调制过的激光注入锁定到两个伺服激光器、利用电子锁相环路将两台频差在数GHz激光器的位相锁定等等。本文通过直接对减反膜外腔反馈半导体激光器进行电流调制的方法,得到了两束位相锁定且频率差在6.0GHz-9.3GHz范围内连续可调的激光,其中6.835GHz和9.192GHz分别对应Rb87和Cs133原子基态超精细能级之间的频率差,激光功率分别可以达到6.87mW和5.09mW。根据减反膜外腔反馈半导体激光器的特点,我们通过调整外腔腔长、激光器工作温度、电流以及所加射频调制信号的功率和频率,在调制频率小于等于4.0GHz时可以将载波完全压制。调制频率大于4.0GHz时,我们虽不能将载波完全压制,但由于外腔与调制频率共振时对调制的增强也得到了调制深度很高的激光,并对其中的物理机制作了分析。基于该拉曼光源我们分析了制备脉冲拉曼光源的方案以及腔QED实验中产生确定性单光子源的方案。本文的另外一部分工作是关于实验室新建立的腔QED系统上的激光频率链。这部分在腔QED实验中对锁定光学微腔的作用是不可替代的。我们简要介绍了腔QED实验研究的发展历史、激光频率链的工作原理以及对腔QED实验的意义、实验室新建的腔QED系统的具体参数等等。我们还设计并制作了搭建频率链系统所需的传导腔,并对传导腔的参数进行了测量。基于该传导腔我们设计并搭建了用于锁定两个光学微腔的激光频率链系统,并且提出了两个光学微腔的锁定步骤。此外我们将频率链系统和新系统上做的工作结合,提出了实现两原子纠缠的实验设想。更多还原

【Abstract】 The phase-locked two laser beams with a tunable and controllable frequency difference in the range of several GHz play a major role in the stimulated Raman transition, coherent population trapping, quantum state preparation and other researches in quantum manipulation. In recent years people have paid great attention to obtain it with simple and reliable means and several methods have been presented to create such kind of light source, such as:injection locking of two slave lasers with a laser modulated by AOM or EOM, injection locking of two slave lasers with the laser from the semiconductor laser with modulated current and coherent combining of the outputs of two semiconductor lasers using optical phase-lock loops. We have demonstrated the laser beams with a tunable frequency difference in the range of6.0GHz-9.3GHz. In particular, the frequency difference of6.835GHz and9.192GHz, corresponding to the ground state hyperfine splitting of Rb87and Cs133respectively, has been experimentally realized. The power of the modulated beam has been measured to be6.87mW which is high enough to generate deterministic single photons by the stimulated Raman Adiabatic Passage (STIRAP). With an antireflection-coated edge-emitting diode placed in an external cavity we can suppress the carrier completely when the modulation frequency is lower than4.0GHz by means of adjusting the external cavity length, the temperature, the current of the diode and power of the modulation. When the modulation is higher than4.0GHz we can’t fully suppress the carrier, but we can also get the laser beams with high modulation depth due to modulation enhancement by external cavity resonance. We can get the cw Raman laser easily by a mode filter, for example an etalon. Additionally, we discuss the scheme to prepare pulse Raman laser beams and deterministic generation of single photons based on the present experiment system.Another part of this thesis is the laser frequency chain, which plays an important role in locking the optical micro cavity of our new cavity QED system. We briefly introduce the history of the cavity QED experiment, the basic idea and mechanism of the laser frequency chain, its significance for the Cavity QED and the specific parameters of our new cavity QED system. We have also designed and made the transfer cavity for the laser frequency chain and tested the parameters. We have set up the laser frequency chain to lock two micro cavities and put forward into locking steps. It is demonstrated that the new transfer cavity is much more robust against the change of temperature than the former one. We can lock the852nm laser,828nm laser and the transfer cavity much better than the former frequency chain system. Hopefully the micro cavity can be locked much better. We will combine the laser frequency system and the cold atom system to study the entanglement of the two distant atoms in two cavities.更多还原