Stimulated emission spectrum of an XeCl laser

Factors responsible for the width of the stimulated emission spectrum of an XeCl laser are discussed. It is found that at high intracavity intensities ($\gtrsim 10$ MW/cm$^2$) the spectral width is governed by the deformation of the gain profile near the maximum due to weak saturation of the rate of rotational exchange. At fairly high input energies ($>0.2$ J/cm$^3$), heating of the active medium during a pump pulse shifts the gain maximum and this also broadens the spectrum obtained by time-integrated recording. The experimental data are in good agreement with the proposed analytic model.