Observation of the strong magneto-optical rotation of the polarization of light in rubidium vapor for applications in atomic magnetometry

Nonlinear resonances in alkali metal vapor, which are detected by the magneto-optical rotation of the linear polarization of light, are actively used in quantum magnetometry to fabricate atomic magnetometers. The magneto-optical rotation in most such sensors is due to magnetic birefringence, and rotation angles usually do not exceed tens of milliradians. In this work, an experiment where magneto-optical resonances of linear polarization rotation of a probe wave are due to strong dichroism induced in a medium by a counterpropagating pump wave has been proposed. Both waves are in resonance with the $F_g=2\to F_c=1$ optical transition in the $^{87}$Rb $D_1$ line ($\lambda\approx 795$ nm). Experiments have been carried out with a $2$-cm-long cylindrical cell filled with a buffer gas, and the maximum rotation angle is $\approx390$ mrad ($22^\circ$) at a width of resonance of about $300$ nT. The results show that the configuration proposed for the observation of magneto-optical rotation is promising for the fabrication of compact high-sensitivity atomic magnetometers.