Elliptical meta-polarizer with homogenized optical field for chip-scale optically pumped magnetometers

Abstract

Due to ultrahigh sensitivity and non-invasive characteristics, spin-exchange-relaxation-free (SERF) atomic magnetometers (OPMs) have attracted increasing attention, leading to a strong demand for device miniaturization, high resolution, and high sensitivity. However, the complex optical components and bulky optical paths of conventional atomic magnetometers hinder their chip-scale integration. In this study, a monolithic elliptical-polarization metasurface is proposed for chip-scale atomic magnetometers, enabling the pumping and detection of elliptically polarized light with a uniform optical field. The proposed metasurface polarizer is designed based on a diatomic metasurface architecture, and by utilizing the far-field interference effect, an ellipticity dichroism of approximately 0.77 is achieved at a wavelength of 795 nm. Its core functionality lies in the fact that, regardless of the polarization state of the incident light, the transmitted light is maintained almost always as a predefined optimal flat-top elliptical polarization state (with ellipticity angle χ = ±22.5°). This metasurface can serve as a replacement for conventional discrete polarizing elements, offering advantages such as small size, integrability, high polarization uniformity, and polarization control without the need for alignment. It thus provides a key optical component design strategy for the realization of high-performance chip-scale quantum sensors.