Physical Review A
Theory of coherent Stark nonlinear spectroscopy in a three-level system
Yurii V. Loiko, Carles Serrat
Abstract
Coherent Stark nonlinear spectroscopy (CSNS) is a spectroscopic tool based on the cancellation of the phase sensitivity at frequency $5\ensuremath{\omega}$ in the ultrafast four-wave mixing (FWM) of two-color pulses with frequencies $\ensuremath{\omega}$ and $3\ensuremath{\omega}$. We develop a theory for CSNS in three-level V-type systems, and reveal that the mechanism for the phase sensitivity at $5\ensuremath{\omega}$ is the quantum interference between the two primary paths in the FWM of the $\ensuremath{\omega}$ and $3\ensuremath{\omega}$ fields. We find that the cancellation phenomenon occurs when the probability amplitude of one of these two primary pathways becomes equal to zero due to the competition effect between the two allowed transitions in the V-type system. The analytical expressions that describe the phase-sensitivity phenomenon and the conditions for its cancellation have been derived on the basis of perturbation theory, and are confirmed by numerical integration of the density matrix and Maxwell equations. We argue that CSNS can be utilized, in particular, for the investigation of optically dense media.