Monolithic metasurface for ultra-stable nuclear spin frequency for miniaturized NMR optical pumping

Miniaturized nuclear magnetic resonance (NMR) co-magnetometers serve as critical platforms for high-precision inertial and magnetic sensing. However, their development has been fundamentally constrained by the trade-off between system compactness and the demanding optical requirements for atomic spin pumping. In this work, a phase-polarization joint modulation design strategy is employed to achieve the functional integration of beam collimation and high-efficiency circular polarization generation on a single metasurface. The resulting device delivers outstanding optical performance, including a circular polarization purity of 97.09% and a highly collimated output with a divergence half-angle of 4.06 mrad. Moreover, through targeted optimization and systematic validation addressing practical performance bottlenecks, the metasurface enables both significant miniaturization potential and a high level of precision in nuclear spin frequency stability. When integrated into an NMR co-magnetometer, the system exhibits an ultra-stable frequency instability of 2.239 × 10^-6 Hz, demonstrating concurrent breakthroughs in device integration and sensing capability. This work establishes a new paradigm for fully integrated optical pumping and provides a scalable pathway toward chip-scale quantum sensors.