Inversionless gain in a three-level system driven by a strong field and collisions

Inversionless gain in a degenerate three-level system driven by a strong ex ternal field and by collisions with a buffer gas is investigated. The mecha nism of population distribution in upper laser level, contributed by the co llision transfer, as well as by relaxation, induced by pressure of a buffer gas, is discussed in detail. Explicit formulae for analysis of optimal con ditions are derived. The idea developed here for the incoherent pump could be generalized to other systems.