Effects of power broadening on NMOR of alkali atoms with partially resolved hyperfine structure

Abstract

This study investigates the effects of power broadening on nonlinear magneto-optical rotation (NMOR) magnetometers. As the laser power increases, the interference between two partially resolved transitions of 87Rb induced by velocity-changing collisions can be exacerbated by power broadening, resulting in a reduction of the rotation rate, and the shift of the optimal laser frequency corresponding to the maximum rotation rate. The theoretical model of NMOR is established using a four-level double Λ scheme, which takes into account power broadening effects, and experimentally studied in a single-beam NMOR magnetometer with a buffer-gas filled cell. The results indicate that the significant enhancement in rotation rate can be achieved by tuning the laser frequency to the optimal detuning based on our model. This study holds considerable importance for the improvement of magnetic field sensitivity in NMOR magnetometers.