Compact power stabilization approach for amplified lasers based on a dual-loop ADRC strategy

A unified compact amplified laser (AL) architecture improves the cross-channel consistency of multichannel optically pumped magnetometer (OPM) arrays in high-resolution biological magnetic field imaging. However, long-period oscillations in free-running ALs’ power severely degrade the sensitivity of OPM arrays. This effect is exacerbated by external thermal disturbances, system model uncertainties, and feedback sensor noise. To address these challenges, we propose a compact power stabilization approach for ALs based on an innovative dual-loop active disturbance rejection control (DLADRC) strategy. A comprehensive quantitative stability analysis is presented for the proposed DLADRC system, with explicit exponential decay estimates for the dynamics of observation and control errors. Compared to the standard ADRC benchmark, the DLADRC achieves superior long-term stability across a broad operational range of 1W to 2W, reducing 1-hour relative power fluctuation by more than 57.1% and decreasing the Allan variance across 100s–1000s by a factor of ten. Owing to the enhanced robustness and the reduced sensor noise susceptibility of DLADRC, our space-saving power stabilization approach demonstrates a relative power fluctuation of 0.05% with a single photodetector, comparable to that of space-consuming optical methods with extra optics. The proposed practical approach enhances the long-term power stability of ALs across their entire operating range at low cost. This work opens the doors to implementing AL-based OPM arrays in clinical diagnostics.