Hybrid active-passive optical stabilization for field-deployable atom gravimetry

In this paper, the authors report a compact, quasi-monolithic optical distribution module (220 mm × 170 mm × 65 mm) developed toward field-deployable 87Rb atom gravimetry. The module combines a Zerodur substrate with a PR-20 piezoelectric rotation stage having a closed-loop angular resolution of 3.5 μrad. The stage drives one wedge in a compact double-wedge layout and provides local correction along a calibrated one-dimensional actuator trajectory. Without active correction, the Raman-path fiber-coupled power decreased to 42% of its 25°C baseline under a 10°C chamber condition; one-dimensional active correction recovered it to approximately 80%. In atom-interferometer operation under the same cold condition, 100 consecutive k-reversal scan pairs showed that the branch-averaged fitted fringe visibility increased from 15.65% to 29.28%, a 1.87-fold improvement. The controller performs local search followed by bounded setpoint maintenance on a calibrated monotonic branch. These results demonstrate optical-delivery stabilization during controlled 10°C–40°C thermal cycling and fringe-visibility recovery at 10°C, providing a compact route toward more robust transportable quantum sensors.