Bell–Bloom Magnetometer Linearization by Intensity Modulation Cancellation

This paper describes a technique for enhancing the linearity of a Bell-Bloom optical magnetometer. Both the M
_x
and Bell-Bloom magnetometers are examined, and the characteristics of their photodetector signals are compared. It is noted that the phase signal has better linearity than the quadrature amplitude signal for a M
_x
magnetometer, while phase and quadrature amplitude give similar performance in Bell-Bloom. A cancellation technique is proposed whereby the laser intensity modulation of Bell-Bloom is mitigated to improve the linearity. A cesium microfabricated atomic magnetometer in a frequency-locked-loop configuration is demonstrated, and the improved slew rate and frequency-domain linearity are shown. This linearity enhancement should prove useful for operating atomic magnetometers in interference-rich environments outside of magnetic shields.