Optically pumped atomic magnetometer based on a polarization-selective metalens

Abstract

Atomic magnetometers (AMs) are promising for biomagnetic measurement, inertial navigation, and quantum precision sensing. Conventional optical-pumping modules, however, rely on discrete polarizers, wave plates, lenses, and mechanical alignment structures, which makes it difficult to meet the requirements of chip-scale arrays for miniaturization, stability, and batch fabrication. This paper proposes an optical-pumping scheme based on a polarization-selective metalens (PSML). By combining chirality-selective transmission with Pancharatnam-Berry phase control, the proposed PSML simultaneously realizes circular-polarization selection, target-handedness conversion, and transmitted-wavefront focusing in a single planar element. A four-atom meta-molecule composed of two half-wave-plate-like meta-atoms is designed, and the output circular-polarization phase is controlled by rotating the meta-atoms. Full-wave simulations show that, at 795 nm, the designed PSML achieves a transmitted circular-polarization dichroism (TCPD) of about 0.87 and a focusing efficiency of 76.9%. Under linearly polarized vertical-cavity surface-emitting laser (VCSEL) illumination, the output Stokes parameters indicate that the transmitted field is close to the target left-handed circularly polarized state. The proposed scheme reduces the number of discrete elements in the optical-pumping front end, lowers optical-path volume and alignment complexity, and provides a scalable integrated optical interface for chip-scale atomic magnetometer arrays.