A modified analytical model of the alkali-metal atomic magnetometer employing longitudinal carrier field* *Project supported by the Hunan Graduate Research and Innovation Project (Grant No. CX2018B009), the Natural Science Foundation of Hunan (Grant No. 2018JJ3608), the Research Project of National University of Defense Technology (Grant Nos. ZK170204 and ZZKY-YX-07-02), and the National Natural Science Foundation of China (Grant Nos. 61671458

Abstract

Alkali-metal atomic magnetometers employing longitudinal carrier magnetic field have ultrahigh sensitivity to measure transverse magnetic fields and have been applied in a variety of precise-measurement science and technologies. In practice, the magnetometer response is not rigorously proportional to the measured transverse magnetic fields and the existing fundamental analytical model of this magnetometer is effective only when the amplitudes of the measured fields are very small. In this paper, we present a modified analytical model to characterize the practical performance of the magnetometer more definitely. We find out how the longitudinal magnetization of the alkali metal atoms vary with larger transverse fields. The linear-response capacity of the magnetometer is determined by these factors: the amplitude and frequency of the longitudinal carrier field, longitudinal and transverse spin relaxation time of the alkali spins and rotation frequency of the transverse fields. We give a detailed and rigorous theoretical derivation by using the perturbation-iteration method and simulation experiments are conducted to verify the validity and correctness of the proposed modified model. This model can be helpful for measuring larger fields more accurately and configuring a desirable magnetometer with proper linear range.