Elliptically Polarized SERF Magnetometers Enabled by High-Transmittance Metasurface

Spin-exchange relaxation-free (SERF) magnetometers that famous for emerging application in the field of biomagnetism imaging, face challenges of miniaturization due to bulky optical components. This study introduces a high-transmittance meta-polarizer designed by combining metasurface polarization transformation method with particle swarm optimization (PSO). This meta-polarizer comprises a$\mathbf{5 0 0}$nm-thick silicon-rich silicon nitride layer on a$\text{SiO}_{2}$substrate, achieving an ellipticity angle of 22.62 degrees (with 0.5 % deviation from the target of 22.5 degrees) and a transmittance of 97.8 % at 795 nm. By optimizing transmittance while preserving target ellipticity, this design significantly reduces the dissipation of transmitted light energy and the volume of SERF magnetometers, overcoming traditional design limitations. This work provides an approach for future all-integrated SERF magnetometers and paves the way for wearable and high-resolution biomagnetism imaging.