Spectral profiles of strongly saturated resonance transitions in high-density rb vapor

We study a nonlinear selective reflection from an interface YAG/high density vapor of the natural mixture of Rb isotopes at the components of 5S(1/2) - 5P(3/2) transition. The Doppler width is small by compare with the dipole-dipole interactions induced width of 6.1 GHz. In the experiment a cw laser beam with a variable intensity is used. There are two main contributions to the effective spectral linewidth: the excitation dependent dipole broadening, and the field broadening which defined by the Rabi frequency. At moderate laser beam intensities, when the Rabi frequency is less than the excitation-reduced dipole broadening, a remarkable narrowing of the spectral profiles is observed. At high intensities, when the Rabi frequency exceeds the reduced dipole broadening, the spectral profiles are practically independent of the laser intensity. This effect can be attributed to intensity induced saturation of the dipole broadening and the strong reduction of the field broadening. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study investigates the nonlinear selective reflection of natural mixtures of Rb isotopes on the interface of YAG/high density vapor. The experimental results show that the spectral profiles significantly narrow at moderate laser beam intensities, while they are practically independent of the laser intensity at high intensities. This effect can be attributed to the intensity-induced saturation of the dipole broadening and the strong reduction of the field broadening.