Stimulated emission due to Doppler-free transitions in optically pumped lasers

An analysis is made of conditions for achieving amplification due to transitions whose Doppler broadening is eliminated (under optical pumping) by light shifts which depend on the atomic velocity. An investigation is made of the spectral characteristics of this amplification process and of the features of lasing due to these transitions. The advantages of lasing due to this type of pumping are shown and possibilities for achieving unidirectional lasing in ring resonators are indicated.