Investigation of basic process of multi-photon laser oscillation by using dressed atom as gain medium

本课题的目的是获取实现多光子激光振荡器所需的基本光谱数据。我们构建了一个扩展腔二极管激光系统和铷原子磁光阱的真空室。在计算机控制下，二极管激光器的频率稳定并锁定在铷原子的一个超精细跃迁上。首先，我们利用二极管激光系统对密封在玻璃电池中的铷原子进行了饱和光谱分析。我们观察到^<85>Rb和^<87>Rb的超精细亚能级之间的光学跃迁。光谱分辨率约为10MHz，由过渡的自然线宽决定。通过改变激光器的偏振度或外加磁场，可以得到不同的饱和光谱。我们分析了大部分的光谱。接下来，我们用磁光捕获铷原子。大约10^5个原子被困在约1mm^3的陷阱区域。原子密度几乎是1992年Mossberg用于双光子激光振荡的Ba原子束密度的100倍。我们现在正在继续研究多光子激光振荡的基本过程。我们将制造一个更大的真空腔，并在腔内放置一个高精细度的光腔来实现双光子激光振荡器。

The purpose of this project is to obtain the basic spectroscopic data for realizing the multi-photon laser oscillator.We constructed an extended cavity diode laser system and a vacuum chamber for the magneto-optical trap of rubidum atoms. The frequency of the diode laser is stabilized and locked to one of the hyperfine transitions of rubidium atom under the computer control.At first, by using the diode laser system, we performed a saturation spectroscopy of rubidium atom which is sealed in a glass cell. We observed the optical transitions between hyperfine sublevels of ^<85>Rb and ^<87>Rb. Spectral resolution is about 10MHz, which is determined by the natural linewidth of the transitions. A various kind of saturation spectra is obtained if we changed the polarization of the lasers or the external magnetic field. We analyzed most of those spectra.Next, we trapped rubidium atoms magneto-optically. About 10^5 atoms were trapped in the trap region of about 1mm^3. The atom density was almost 100 times as dense as that of the atomic beam of Ba which was used for the two-photon laser oscillation by Mossberg in 1992.We are now continuing our investigation of the basic process of the multi-photon laser oscillation. We will make a larger vacuum chamber and put a high finesse optical cavity in the chamber to realize the two-photon laser oscillator.