Amplification and nonlinear losses in a cw CO2 laser with fast axial flow

A study is reported of the influence of a laser mixture relaxing outside the discharge zone on the parameters of the radiation emitted by a cw CO₂ laser. It is shown that resonant nonlinear absorption of the radiation may appear, in a certain range of the laser parameters, behind the discharge zone. The dependence of such absorption on the radiation intensity is complex because of saturation and also because of a change in the relaxation length of excited molecules in the radiation field. The reflection coefficient of the exit mirror and its geometric parameters ensuring the maximum laser efficiency are determined, taking account of the additional amplification in the relaxing laser mixture.