The Bell-Bloom-type optically-pumped FID Rubidium atomic magnetometer with a multi-passing probe beam and two counter-propagating pump beams

TL;DR

This paper introduces an improved Bell-Bloom rubidium FID magnetometer with counter-propagating pump beams and multi-pass detection, significantly enhancing measurement accuracy and sensitivity for weak magnetic fields.

Contribution

The study presents a novel magnetometer design that homogenizes atomic spin polarization and boosts signal strength, outperforming traditional single-beam, single-pass setups.

Findings

Magnetic field sensitivity improved from 18.9 pT/√Hz to 3.1 pT/√Hz.

Homogenized atomic spin polarization reduces measurement errors.

Multi-pass probe enhances signal amplitude significantly.

Abstract

The Bell-Bloom-type optically pumped atomic magnetometers are well suited for weak geomagnetic field detection. However, conventional single-beam pumping introduces an atomic spin polarization gradient, which limits the measurement accuracy and sensitivity. To address this issue, this paper proposes and experimentally demonstrates a Bell-Bloom-type rubidium FID magnetometer scheme integrating orthogonally polarized counter-propagating pumping and multi-pass probe detection. This design homogenizes the atomic spin polarization distribution and suppresses light shifts and power broadening effects induced by the pump beam. Meanwhile, the five-pass probe configuration significantly enhances the signal amplitude. Experimental results reveal that, compared with the traditional single-beam pumping and single-pass detection scheme, the proposed magnetometer achieves a remarkable improvement in magnetic field measurement accuracy, and the magnetic field sensitivity is improved from 18.9 pT/\sqrt{Hz} to 3.1 pT/\sqrt{Hz}. This work provides an effective technical approach and reference for optimizing the performance of atomic magnetometers and extending their applications in integrated arrays.