Experimental investigations of absorption and dispersion profiles of a strongly driven transition:<i>ssV</i>-shaped three-level system with a strong probe

Abstract

This paper reports on experimental investigations of absorption, dispersion, and amplitude profiles of the Autler-Townes doublet in a ssV-shaped three-level system where the probe field intensities varied from weak to strong. The experiments were carried out on the ground-state hyperfine transitions of the nitrogen-vacancy color center in diamond using the Raman heterodyne technique, a sensitive optically detected magnetic resonance technique. A strong pump field is on resonance with the ${\mathit{I}}_{\mathit{z}}$=\ensuremath{\Vert}0〉\ensuremath{\leftrightarrows}\ensuremath{\Vert}1〉 transition at 4.7 MHz and the resultant Autler-Townes profiles are probed with a separate field scanning through the ${\mathit{I}}_{\mathit{z}}$=\ensuremath{\Vert}0〉\ensuremath{\leftrightarrows}\ensuremath{\Vert}-1〉 transition at 5.4 MHz. As the probe power increases the absorptive profile of the Autler-Townes doublet becomes saturated and power broadened and the two components overlap constructively. In contrast, the inner parts of the two dispersive doublet components interfere destructively due to a \ensuremath{\pi} phase difference. The amplitude profile has an anomalous line shape at high probe intensity due to the different saturation behaviors of the absorptive and dispersive components. The experimental profiles are in good agreement with theoretical profiles calculated by solving the equation of motion of the density matrix under the steady-state limit.