Yun Peter, Tan Bozhong, Deng Wei, Gu Sihong
Key Laboratory of Atomic Frequency Standards, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China.
Rev Sci Instrum. 2011 Dec;82(12):123104. doi: 10.1063/1.3665986.
To prepare the coherent population trapping (CPT) states with rubidium and cesium, the commonly used atoms in CPT studies, a coherent bi-chromatic light field with frequency difference of several GHz is a basic requirement. With a 200 MHz center frequency acousto-optic modulator (AOM), we have realized bi-chromatic laser fields with several GHz frequency splits through high diffraction orders. We have experimentally studied the coherence between two frequency components of a bi-chromatic laser beam, which is composed of ±6 orders with frequency split of 3 GHz diffracted from the same laser beam, and the measured residual phase noise is Δφ(2)<0.019 rad(2). The bi-chromatic laser fields were used to prepare CPT states with (85)Rb and (87)Rb atoms, and high contrast CPT signals were obtained. For CPT states preparation, our study result shows that it is a feasible approach to generate the bi-chromatic light field with larger frequency splits through high diffraction orders of AOM.
为了利用铷和铯（相干布居囚禁（CPT）研究中常用的原子）制备CPT态，一个频率差为几吉赫兹的相干双色光场是基本要求。利用一个中心频率为200兆赫兹的声光调制器（AOM），我们通过高衍射级实现了具有几吉赫兹频率分裂的双色激光场。我们对由同一激光束衍射产生的频率分裂为3吉赫兹的±6级组成的双色激光束的两个频率分量之间的相干性进行了实验研究，测量得到的残余相位噪声为Δφ(2)<0.019 rad(2)。该双色激光场被用于用（85）Rb和（87）Rb原子制备CPT态，并获得了高对比度的CPT信号。对于CPT态的制备，我们的研究结果表明，通过AOM的高衍射级产生具有更大频率分裂的双色光场是一种可行的方法。
