Spin-Exchange-Relaxation-Free Magnetometry Using Elliptically-Polarized Light

TL;DR

This paper introduces a high-sensitivity alkali-metal magnetometer utilizing elliptically-polarized light, simplifying optical pumping and detection in spin-exchange relaxation-free conditions, achieving femtotesla sensitivity in a compact device.

Contribution

The authors demonstrate a novel Rb magnetometer using a single elliptically-polarized laser beam, improving simplicity and sensitivity over traditional methods.

Findings

Achieved magnetic field sensitivity of 7 fT/√Hz.

Used a compact 5x5x5 mm Rb vapor cell.

Implemented modulation to shift signals to high frequencies.

Abstract

Spin-exchange relaxation free alkali-metal magnetometers typically operate in the regime of high optical density, presenting challenges for simple and efficient optical pumping and detection. We describe a high-sensitivity Rb magnetometer using a single elliptically-polarized off-resonant laser beam. Circular component of the light creates relatively uniform spin polarization while the linear component is used to measure optical rotation generated by the atoms. Modulation of the atomic spin direction with an oscillating magnetic field shifts the detected signal to high frequencies. Using a fiber-coupled DFB laser we achieve magnetic field sensitivity of 7 fT/$\sqrt{% \mathrm{Hz}}$ with a miniature $5\times5\times5$ mm Rb vapor cell.