Compact Amplified Laser Power Stabilization Using Robust Active Disturbance Rejection Control with Sensor Noise Decoupling

TL;DR

This paper introduces a dual-loop active disturbance rejection control method to stabilize laser power in optically pumped magnetometers, significantly reducing power instability and noise effects for enhanced biomagnetic detection.

Contribution

It proposes a novel DLADRC strategy with stability analysis for laser power stabilization, improving long-term stability and noise decoupling in AL-based OPM systems.

Findings

Over 85.7% reduction in 1-hour power instability

Tenfold decrease in Allan variance for 10^2 to 10^3 seconds

Robust effectiveness across diverse operating scenarios

Abstract

Laser power instability, encompassing random jitter and slow drift, severely limits the performance of optically pumped magnetometers (OPMs) in detecting ultra-weak magnetic fields, especially in large-scale OPM arrays for magnetoencephalography. Although a unified amplified laser (AL) architecture improves integration, fluctuations in the pump beam progressively degrade performance across all channels, exacerbated by environmental disturbances and system uncertainties. To address this challenge, this paper presents a compact AL power stabilization approach based on an innovative dual-loop active disturbance rejection control (DLADRC) strategy, while integrating a comprehensive quantitative stability analysis through novel exponential decay estimates for extended state observers (ESOs) and control error dynamics. As validated through physical experimental results, the proposed method significantly improves AL's long-term stability with sensor noise decoupling, achieving an over 85.7% reduction in 1-hour power instability and a tenfold decrease in Allan variance for correlation times 10^2 s--10^3 s, compared to standard ADRC. Crucially, the strategy demonstrates robust effectiveness across diverse operating scenarios, enabling AL-based OPM systems to achieve their full potential in high-sensitivity biomagnetic field detection.