Dispersion laws of a highly excited three-level atom with an equidistant energy spectrum

A dispersion law for the system of three-level atoms with an equidistant energy spectrum interacting with resonant laser radiation has been obtained taking into account two successive optically allowed one-photon transitions and an optically allowed two-photon transition between the lower and upper levels. It has been shown that the dispersion law consists of three polariton branches. The effects of repulsion and attraction of branches of the dispersion law and their intersection, as well as the self-consistent variation of the photon-atom coupling constant, have been predicted.