Fang Jiancheng, Wang Tao, Zhang Hong, Li Yang, Zou Sheng
School of Instrument Science and Opto-Electronics Engineering, Beihang University, Beijing 100191, China.
School of Instrument Science and Engineering, Southeast University, Nanjing 210096, China.
Rev Sci Instrum. 2014 Dec;85(12):123104. doi: 10.1063/1.4902567.
The hybrid optical pumping atomic magnetometers have not realized its theoretical sensitivity, the optimization is critical for optimal performance. The optimizations proposed in this paper are suitable for hybrid optical pumping atomic magnetometer, which contains two alkali species. To optimize the parameters, the dynamic equations of spin evolution with two alkali species were solved, whose steady-state solution is used to optimize the parameters. The demand of the power of the pump beam is large for hybrid optical pumping. Moreover, the sensitivity of the hybrid optical pumping magnetometer increases with the increase of the power density of the pump beam. The density ratio between the two alkali species is especially important for hybrid optical pumping magnetometer. A simple expression for optimizing the density ratio is proposed in this paper, which can help to determine the mole faction of the alkali atoms in fabricating the hybrid cell before the cell is sealed. The spin-exchange rate between the two alkali species is proportional to the saturated density of the alkali vapor, which is highly dependent on the temperature of the cell. Consequently, the sensitivity of the hybrid optical pumping magnetometer is dependent on the temperature of the cell. We proposed the thermal optimization of the hybrid cell for a hybrid optical pumping magnetometer, which can improve the sensitivity especially when the power of the pump beam is low. With these optimizations, a sensitivity of approximately 5 fT/Hz(1/2) is achieved with gradiometer arrangement.
混合光泵浦原子磁力仪尚未实现其理论灵敏度，优化对于实现最佳性能至关重要。本文提出的优化方法适用于包含两种碱金属种类的混合光泵浦原子磁力仪。为了优化参数，求解了两种碱金属种类的自旋演化动力学方程，并利用其稳态解来优化参数。混合光泵浦对泵浦光束的功率要求较大。此外，混合光泵浦磁力仪的灵敏度随泵浦光束功率密度的增加而提高。两种碱金属种类之间的密度比对于混合光泵浦磁力仪尤为重要。本文提出了一个优化密度比的简单表达式，它有助于在密封混合池之前确定制造混合池时碱金属原子的摩尔分数。两种碱金属种类之间的自旋交换速率与碱金属蒸汽的饱和密度成正比，而饱和密度高度依赖于混合池的温度。因此，混合光泵浦磁力仪 的灵敏度取决于混合池的温度。我们提出了用于混合光泵浦磁力仪的混合池热优化方法，该方法可以提高灵敏度，特别是在泵浦光束功率较低时。通过这些优化，采用梯度仪配置可实现约5 fT/Hz(1/2) 的灵敏度。
