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

TLDR: In this paper, a high-sensitivity Rb magnetometer using a single elliptically-polarized off-resonant laser beam is described. But the magnetic field sensitivity of the magnetometer is limited to 7 fT/$\sqrt{% \mathrm{Hz}.

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.