All-optical atomic magnetometry using an elliptically polarized amplitude-modulated light wave

We study a resonant interaction of an elliptically polarized light wave with ⁸⁷Rb vapor D$₁$ line exposed to a transverse magnetic field. A 5times5times5 mm³ glass vapor cell is used for the experiments. The wave intensity is modulated at the frequency Ω_m. By scanning Ω_m near the Larmor frequency Ω_L, a magnetic resonance (MR) can be observed as a change in the ellipticity parameter of the wave polarization. This method for observing MR allows to significantly improve the signal-to-noise ratio compared to a classical Bell-Bloom scheme using a circularly polarized wave. The sensitivity of the magnetic field sensor is estimated to be approx 130 fT/surdHz in a 2 kHz bandwidth, confidently competing with widely used Faraday-rotation Bell-Bloom schemes. The results can be used to develop a miniature all-optical magnetic field sensor for medicine and geophysics.