SERF magnetometer array using concurrent amplitude-stabilized optical modulation

We demonstrate a compact atomic magnetometer array that uses concurrent amplitude-stabilized optical modulation (CASOM) to improve the low-frequency performance and long-term stability for bio-magnetic measurements. The system is integrated by a high-power laser, a fiber-optic splitting module, an electronic control unit and dual-beam orthogonal sensors, each with a sensor volume of 7.8 cm³ . The proposed CASOM technique employs a single acousto-optic modulator to achieve both intensity stabilization and high-frequency amplitude modulation of the probe light. Compared to the conventional DC scheme, experimental results in a single-channel CASOM-based configuration show a onefold increase in sensitivity within the frequency range of 1–10 Hz and a 57 % reduction in sensitivity standard deviations over 2-hour intervals. This demonstrates significant suppression of low-frequency noise and improved long-term stability in the magnetometer. Building on the CASOM method, the magnetometer array realizes an average sensitivity of approximately 7 fT/Hz 1/2 across the bandwidth of 64 Hz, with sensitivity standard deviations under 0.3 fT/Hz 1/2 across all channels. The CASOM-based array exhibits excellent and stable multi-channel measurement performance throughout the entire frequency spectrum. Moreover, the array shows high measurement consistency within 10–100 pT, with measurement errors below 0.76 pT and non-linear errors less than 2 %. Compared with traditional DC configurations and magnetic field modulation setups, this configuration eliminates magnetic crosstalk while simultaneously suppressing low-frequency noise and optical fluctuations, which is particularly suitable for bio-magnetic measurements that require long-term stability and low-frequency sensitivity.