Microfabricated 3D Optimized Rubidium Vapor Cell Array for Low Cost Atomic Magnetometer

Wearable biomagnetic field mapping with multiple-channel atomic magnetometers (AMs) requires low-cost microfabricated rubidium vapor cell arrays (RVCAs) of high performance. In this letter, an innovative microfabricated 3D RVCA with optimized polarization lifetime is proposed and demonstrated at a wafer level. To characterize the influence of vapor cell geometry on polarization lifetime, the 3D RVCA with four interconnected light-atom interaction chambers of uniform internal buffer gas pressure (0.7 amg) and various surface-to-volume ratios (17.61, 18.15, 20.95, and 27.14 cm-1) are prepared. For the first time, we utilize single-beam configuration to characterize microfabricated 3D RVCA by extrapolating to vanishing light intensity. We measure the intrinsic polarization lifetime of the four chambers within an 3D RVCA. The results indicate that decreasing the surface-to-volume ratio of the chamber in 3D RVCA at 413 K substantially improves the polarization lifetime by 129.3%. Measurements conducted across varying temperature all demonstrate that reductions in surface-to-volume ratios positively influence the enhancement of the polarization lifetime. The proposed RVCA offers critical insights for low-cost and high-performance chip-scale AM array based on microfabricated 3D atomic vapor cells.