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

We study a resonant interaction of an elliptically polarized light wave with Rb-87 vapor (D-1 line) exposed to a transverse magnetic field. A 5x5x5 mm(3) glass vapor cell is used for the experiments. The wave intensity is modulated at the frequency Omega(m). By scanning Omega(m) near the Larmor frequency Omega(L), a magnetic resonance (MR) can be observed as a change in the ellipticity parameter of the wave polarization caused by the circular dichroism of the medium. 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. Under current experimental conditions, the sensitivity of the magnetic field sensor is estimated to be approximate to 130 fT/root Hz in a approximate to 2.1 kHz bandwidth. The proposed technique confidently competes with other widely used Bell-Bloom-like schemes based on the Faraday rotation of the light wave polarization, while being more simple and robust. The results can be used to develop a miniature all-optical magnetic field sensor for medicine and geophysics.