Stimulated emission at the difference-frequency generation of a bichromatic field interacting with a three-level atom

The author considers the stimulated emission process that occurs at the difference-frequency generation of a bichromatic field interacting with a three-level atom in the Lambda configuration. In the low-intensity limit of both laser fields and at finite detunings, there are two induced excitations whose lifetimes are much longer in comparison to those of excitations spontaneously emitted by the excited states of the atom. Conditions are established under which the two-photon stimulated emission prevails, indicating that significant amplification is likely to occur at the difference-frequency generation.