Analytical studies on the coherent AC Stark effect of an open λ-type drive-probe system

The Doppler-free absorptive lineshape and its physical parameters are analytically formulated for an open λ-type coherently prepared drive-probe system. The individual contribution of drive and probe fields on AC Stark splitting is demonstrated through power broadened lineshape. We exhibit the sharpness and asymmetric nature of Stark splitting for probe field induced quantum coherence and atomic coherence. The coherent linear Stark shift due to probe and drive fields is classified by means of various physical controlling parameters. It is shown that the direction of the AC Stark shift towards red or blue region can be controlled via probe field induced quantum coherence.