# Performance Characterization and Optimization of a Miniaturized SERF Atomic Magnetometer via Tunable Laser Power

## TL;DR

Researchers optimized a small magnetic sensor by adjusting laser power, achieving high sensitivity and performance in a compact design.

## Contribution

A power–performance framework was established for miniaturized SERF magnetometers through tunable laser power modulation.

## Key findings

- Sensitivity showed a non-monotonic trend with laser power, peaking at 16 fT/√Hz at 300 μW.
- Bandwidth and dynamic range increased monotonically, reaching 230 Hz and ±5.4 nT at 500 μW.
- Active laser power modulation allows flexible operation modes without hardware changes.

## Abstract

What are the main findings?
The distinct evolutionary trends of sensitivity, bandwidth, and dynamic range were systematically quantified as a function of tunable laser power in a miniaturized SERF magnetometer.An optimized comprehensive performance was achieved within a compact 35 × 22 × 15 mm3 probe, featuring 16 fT/√Hz sensitivity, 230 Hz bandwidth, and a ±5.4 nT dynamic range.

The distinct evolutionary trends of sensitivity, bandwidth, and dynamic range were systematically quantified as a function of tunable laser power in a miniaturized SERF magnetometer.

An optimized comprehensive performance was achieved within a compact 35 × 22 × 15 mm3 probe, featuring 16 fT/√Hz sensitivity, 230 Hz bandwidth, and a ±5.4 nT dynamic range.

What are the implications of the main findings?
Active modulation of laser power enables a flexible transition between ultra-high sensitivity and high-bandwidth operating modes without the need for hardware reconfiguration.The established power–performance framework enhances the environmental adaptability and operational robustness of portable biomagnetic sensing systems in diverse application scenarios.

Active modulation of laser power enables a flexible transition between ultra-high sensitivity and high-bandwidth operating modes without the need for hardware reconfiguration.

The established power–performance framework enhances the environmental adaptability and operational robustness of portable biomagnetic sensing systems in diverse application scenarios.

Spin-exchange relaxation-free (SERF) atomic magnetometers have emerged as highly promising candidates for ultra-weak magnetic field detection, particularly in biomagnetic imaging, owing to their exceptional sensitivity, amenability to miniaturization, and near-room-temperature operation. While current miniaturized magnetometers typically employ laser chips with fixed optical power, the quantitative impact of laser power on critical performance metrics remains to be fully elucidated. This study systematically investigates the influence of laser power on sensitivity, bandwidth, and dynamic range by incorporating considerations of power broadening, saturation absorption, and noise constraints. A miniaturized probe, integrated with an actively controlled vertical-cavity surface-emitting laser (VCSEL), was developed for experimental validation. Theoretical and experimental results consistently demonstrate that as optical power increases, sensitivity exhibits a non-monotonic dependence, whereas both bandwidth and dynamic range manifest a monotonic upward trend, aligning well with theoretical simulations. The optimized sensor achieved a peak sensitivity of 16 fT/√Hz at 300 μW, while the bandwidth and dynamic range reached 230 Hz and ±5.4 nT at 500 μW, respectively. This work establishes a robust theoretical and experimental framework for the comprehensive performance optimization of laser-integrated miniaturized atomic magnetometers.