Influence of a radial inhomogeneity of the active medium on the output radiation power from a cw CO2 laser with fast axial flow

A radial inhomogeneity of the gain in a cw CO₂ laser with fast axial flow was studied experimentally and theoretically. It was found that this inhomogeneity resulted from a radial inhomogeneity of the temperature and contraction of a longitudinal self-sustained discharge towards the axis in a gas-discharge tube. This saturated the rise of the small-signal gain when the total discharge current was increased. It also reduced the rate of rise of the output radiation power with increase in the input energy when the fundamental Gaussian mode was generated.