全光高灵敏度Bell-Bloom磁力仪的实现和优化  

Realization and Optimization of all-optical Cs atom magnetometer based on Bell-Bloom structure

作　　者：张军海[1] 向康[1] 梅红松 赵文辉[1] 黄宗军[1] 孙伟民[1] 

机构地区：[1]哈尔滨工程大学理学院,黑龙江哈尔滨150001

出　　处：《光电子．激光》2015年第2期211-216,共6页Journal of Optoelectronics·Laser

基　　金：国家"863"高技术研究发展计划;航空基金(201207P6002);中央高校基本科研基金(HEUCF20111111)资助项目

摘　　要：为了克服利用交流磁场激发基态塞曼磁子能级跃迁的传统光泵磁力仪信号串扰问题,本文报道了一种基于Bell-Bloom结构的全光铯(Cs)原子磁力仪。利用共振圆偏振光极化基态Cs原子使之产生磁偶极矩,在外磁场条件下,磁矩围绕外场进行拉莫尔进动,通过测量线偏振检测光偏振椭圆长轴的变化周期,可以实现对外磁场的高灵敏度测量。理论分析了强度调制的Bell-Bloom磁力仪工作原理,搭建了试验系统,通过磁力仪参数(抽运激光频率和光强)的优化,在100nT外磁场附近,获得了线宽(半高全宽)为22Hz、每单位带宽信噪比(SNR)达到3.2×104的拉莫尔进动光谱,进而评价该磁力仪物理系统具有100fT/Hz1/2的本征灵敏度;闭环测试结果为120fT/Hz1/2,空间分辨率达到1.2cm,且随外界磁场变化的响应时间为300ms。In order to availably solve the crosstalk of the traditionally optically pumped magnetometer,in which an oscillating magnetic field drives transitions between Zeeman magnetic sublevels, an all-optical cesium （Cs） atomic magnetometer based on Bell-Bloom structure has been investigated and demonstra- ted experimentally in this paper. When there is an external magnetic field,by analyzing the Larmor pre- cession spectrum of the polarized ground state atoms induced by a modulated pump laser, the atomic magnetometer with high sensitivity is achieved. First, we present the operating principle of the magne- tometer with amplitude modulation and set up the experimental system by means of a three-layer mag- netic shield. Then in the case of 100 nT field by optimizing the experimental parameters, i. e. , the fre- quency and intensity of the pump laser, we have obtained the atomic precession spectrum with line width （full width at half maximum） of 22 Hz and signal noise ratio （SNR） of 3. 2× 10 4 per unit hertz band width,and then have evaluated the magnetometer with an intrinsic sensitivity of 100 fT/Hz1/2 and spa- tial resolution smaller than 1.2 cm,while the experimentally closed loop test shows that the cesium a- tomic magnetometer would have the sensitivity of 120 fT/Hz1/2 and response time of 300 ms.

关 键 词：磁力仪 灵敏度 响应时间 空间分辨率 

分 类 号：O433.54[机械工程—光学工程]