脉冲激光抽运铷原子钟研究

Study of Pulsed Optically Pumped Rb Frequency Standard

对脉冲激光抽运、微波分立场共振和自由感应微波辐射或者光吸收检测方案(POP)的铷原子钟进行了理论和实验研究。理论研究表明,POP原子钟,可以消除光频移,有效地减小腔牵引频移,从而有利于提高原子钟的稳定度;且微波脉冲面积为π/2时,微波Ramsey条纹的线宽为传统Ramsey条纹的一半,从而提高了原子品质因数。实验获得了POP铷原子钟的原子自感应微波辐射Ramsey信号和光学Ramsey信号,线宽分别为65 Hz和150 Hz左右;实现了原子钟原理样机的闭环锁定,短期稳定度1.2×10-12-τ1/2(τ=100 s)。

The pulsed optically pumped（POP） 87Rb vapor-cell frequency standard was studied based on the detection of free induction microwave signal or optical absorption signal.In POP operation the pumping,interrogation,and detection phases are separated in time,avoiding the coupling between microwave and optical coherence.The theoretical results show that an oscillation period doubled with respect to the classical Ramsey method which leads to a doubled atomic quality factor Q,and the reduction of optical shift and cavity pulling shift will be obtained,when the atoms are submitted to π/2 Ramsey microwave pulse.In experiment Ramsey fringes were obtained with a clock prototype based on 87Rb in buffer gas,with bandwidth of 65 Hz and 150 Hz for microwave and optical signal respectively.The frequency stability achieved was 1.2×10-12 for measurement times up to 100 s.