Interaction of modes emitted due to adjacent transitions in gas lasers

A theoretical investigation is made of the feasibility of simultaneous laser action due to adjacent transitions in atoms of a gaseous medium with level momenta $j_b\to j_c$ and $j_b\to j_a$. In the case of small relative excesses of the population inversions of the active levels over the threshold, an expression is derived for the region of simultaneous laser action with parallel and orthogonally polarized fields. The limiting cases of homogeneously and inhomogeneously broadened lines are studied. Calculations are made allowing for depolarizing atomic collisions. For a homogeneously broadened line and negligible degeneracy of the levels, a region of simultaneous laser action is found for an arbitrary relative excess of the population inversion over the threshold.