Two-photon laser oscillation by using trapped atoms

我们建立了一个扩展腔半导体激光器系统和一个用于Rb原子磁光陷阱(MOT)的真空室。在计算机控制下，激光频率被稳定并锁定到Rb原子的超精细跃迁。我们对蒸汽室中的Rb原子进行了线性和非线性光谱分析，观察到了^&lt；85&gt；Rb和^&lt；87&gt；Rb的超精细子能级之间的光学跃迁。光谱分辨率约为6 MHz，由跃迁的自然线宽决定。约10 8个Rb原子被MOT囚禁在-1 mm 3中。原子密度几乎是1992年Mossberg首次用于双光子激光振荡的Ba原子束的100倍。我们还对俘获的Rb原子进行了非线性光谱，当我们改变激光偏振配置和外加磁场强度时，观察到了多种光谱。我们对MOT中的预冷原子进行了偏振梯度冷却，得到了超冷的Rb原子(-10muK)。通过使用暗MOT，我们进一步将原子密度提高了50%。我们利用甜甜圈光束发展了一种新型的中性原子的全光陷阱。该陷阱开启了一种简单的原子操纵技术，包括气态原子的玻色-爱因斯坦凝聚。

We constructed an extended-cavity diode laser system and a vacuum chamber for the magneto-optical trap (MOT) of rubidium (Rb) atoms. The laser frequency was stabilized and locked to a hyperfine transition of rubidium atom under the computer control.We performed linear and non-linear spectroscopies of Rb atoms in a vapor cell and observed optical transitions between hyperfine sublevels of ^<85>Rb and ^<87>Rb. Spectral resolution was about 6 MHz and was determined by the natural linewidth of the transitions.About 10^8 Rb atoms were trapped in - 1mm^3 by the MOT.The atomic density was almost 100 times as large as that of the atomic beam of Ba which was first used for the two-photon laser oscillation by Mossberg in 1992. We also performed a non-linear spectroscopy with the trapped Rb atoms and many kinds of spectra were observed when we changed the configuration of laser polarizations and strehgth of the external magnetic field. These spectra were well explained by the dressed-atom picture.Ultracold Rb atoms (- 10muK) were obtained when we applyed a polarization gradient cooling to pre-cooled atoms in the MOT.By using a dark MOT,we further increased the atomic density by 50 % form the density obtained by the normal MOT.We developed a novel all-optical trap for neutral atoms by using a doughnut beam. The trap opens the way to a simple technique for atom manipulation, including Bose-Einstein condensation of gaseous atoms.