Resonant two-photon interference spectra induced by a bichromatic field in the ground state of a three-level atom

The author has considered the interference spectra arising from the competition between absorption and stimulated emission processes, which have been induced by two laser fields operating at a two-photon resonance with a three-level atom in the ' Lambda ' configuration. In the low intensity limit of both laser fields, the induced spectrum in the ground state consists mainly of a peak, whose height and asymmetry depend strongly on the value of the detuning of the laser fields. In the absence of detuning, the height of the induced peak takes positive values implying that the physical process of absorption (attenuation) takes place, while at finite detunings the height of the peak becomes negative indicating the frequencies at which stimulated emission (amplification) is likely to occur. The spectra arising from the emission of a laser photon by the excited state consist of two peaks describing stimulated emission and induced absorption, respectively, where the former dominates the latter for small values of the Rabi frequencies but for higher ones, cancel each other out.