Gaussian beam parameters and their stabilization in gas lasers

Saturation inhomogeneity produced by a Gaussian field in a gas laser and population inhomogeneity are responsible for lens effects which depend on frequency. They give rise to frequency-dependent transverse parameter variations which, in general, result in an asymmetric line shape. The main objective of this paper is to give a method which yields closed-from expressions for these variations and permits their analytical discussion. As an application we determine a laser structure which minimizes the variations in the region around one of the mirrors. It gives a laser which is stabilized in its transverse parameters and is characterized by a symmetric Lamb dip. We experimentally confirm this result using the 3.39-μm line of ${}_{}{}^{20}{}_{}{}^{}\mathrm{Ne}$.