原子磁力仪中的检测光强噪声补偿方法研究  

Study on the noise compensation of the probe light intensity in an atomic magnetometer

作　　者：谢宏泰 康泽豪 XIE Hongtai;KANG Zehao(Changcheng Institute of Metrology&Measurement,Beijing 100095,China;Quantum Sensing Center,Zhejiang Lab.,Hangzhou 310000,China)

机构地区：[1]航空工业北京长城计量测试技术研究所,北京100095 [2]之江实验室量子传感研究中心,浙江杭州310000

出　　处：《计测技术》2024年第2期40-46,共7页Metrology & Measurement Technology

基　　金：国家“十四五”技术基础科研项目(TC220A04Y-2)。

摘　　要：为解决原子磁力仪检测光强残余噪声问题,提出了检测光强噪声数字补偿方法。首先根据原子自旋进动检测基本理论,通过光弹调制器和锁相放大器进行线偏光的光旋角检测,利用噪声衰减器对检测光功率进行正弦调制拟合得到补偿系数,然后使用光弹调制器调制频率的二倍频信号对一倍频信号进行后处理修正,实现检测光强噪声压制。得到补偿系数后可将用于幅度调制的硬件甚至前级稳光强装置移除,仅利用数字补偿技术即可实现光强噪声抑制。搭建基于K-Rb-21Ne气室的磁力仪实验装置,在无自旋交换弛豫态(Spin-Exchange Relaxation-Free,SERF)下开展检测光强噪声补偿实验,结果显示光旋角检测信号的噪声被压制了13.2 dB@3 Hz。应用此噪声补偿方法,避免了不同光路所引入的非共模噪声,并在前级稳光强的基础上实现了二次稳光强。此补偿方法可进行补偿系数的定期校准,减小系统状态改变及不稳定性带来的影响,对于提升原子磁力仪灵敏度具有重要意义。In order to solve the problem of the residual noise of the probe light intensity in atomic magnetometer,a digital compensation method is proposed.Firstly,the basic theory of Larmor process detection is adopted,and the optical rotation angle of the linearly polarized light is detected through a photoelastic modulator and a lock⁃in amplifier.Then,the noise eater is used to obtain the compensation coefficient by sinusoidal modulating the probe light power and fitting the curves,and then the first harmonic component is post⁃corrected with the second harmonic component of the modulating fre⁃quency of the photoelastic modulator to realize the noise suppression of the probe light intensity.The hardware used for the amplitude modulation and even the primary light intensity stabilization device can be removed after obtaining the compen⁃sation coefficient,and the noise suppression can be achieved by using only the digital compensation technique.An atomic magnetometer based on K⁃Rb⁃21Ne vapor is built and carried out the experiment in the spin⁃exchange relaxation⁃free(SERF)regime,in which the results shows the noise of the optical angel detection signal is suppressed by 13.2 [e-mail] applying the noise compensation method,the non⁃common mode noise caused by different optical paths is avoided,and the secondary stabilization is realized on the basis of the primary stabilization of the probe light intensity.The com⁃pensation coefficient can be calibrated regularly,and the influence from the change or instability of the system is reduced.The study is important for the sensitivity improvement of atomic magnetometers.

关 键 词：原子磁力仪 无自旋交换弛豫 检测噪声 噪声补偿 

分 类 号：TB9[一般工业技术—计量学] O562[机械工程—测试计量技术及仪器] TP21[理学—原子与分子物理]