Wu Tianbo, Xiao Wei, Peng Xiang, Wu Teng, Guo Hong
State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Electronics, and Center for Quantum Information Technology, Peking University, Beijing 100871, China.
MIIT Key Laboratory of Complex-field Intelligent Sensing, Advanced Research Institute of Multidisciplinary Science, Beijing Institute of Technology, Beijing 100081, China.
Biomed Opt Express. 2024 Dec 20;16(1):235-244. doi: 10.1364/BOE.545624. eCollection 2025 Jan 1.
Optically-pumped magnetometer (OPM) has been of increasing interest for biomagnetic measurements due to its low cost and portability compared with superconducting quantum interference devices (SQUID). Miniaturized spin-exchange-relaxation-free (SERF) OPMs typically have limited bandwidth (less than a few hundred Hertz), making it difficult to measure high-frequency biomagnetic signals such as the magnetocardiography (MCG) signal of the mouse. Existing experiments mainly use SQUID systems to measure the signal. In this paper, we introduce a prototype miniaturized single-beam SERF magnetometer with a bandwidth of ∼ 1 kHz. Instead of operating the OPM in a closed-loop mode to improve the bandwidth of the OPM, which usually has a poorer performance in high-frequency range, we use the power-broadening effects to shorten the spin relaxation time and thus a faster response to the magnetic fields to be measured. Combined with light power stabilizations to improve both the sensitivity and stability, our magnetometer has a low noise floor of 30 fT / Hz, which has been successfully adopted to measure the MCG signal of the mouse.
与超导量子干涉器件（SQUID）相比，光泵磁力仪（OPM）因其低成本和便携性而在生物磁测量中越来越受到关注。小型化的无自旋交换弛豫（SERF）磁力仪通常带宽有限（小于几百赫兹），这使得测量高频生物磁信号（如小鼠的磁心动图（MCG）信号）变得困难。现有的实验主要使用SQUID系统来测量该信号。在本文中，我们介绍了一种带宽约为1 kHz的小型化单光束SERF磁力仪原型。我们没有采用闭环模式操作OPM来提高其带宽（通常在高频范围内性能较差），而是利用功率展宽效应来缩短自旋弛豫时间，从而更快地响应被测磁场。结合光功率稳定技术以提高灵敏度和稳定性，我们的磁力仪具有30 fT / Hz的低本底噪声，并已成功用于测量小鼠的MCG信号。
