Role of power broadening in influencing maximum gain of far infrared gain material

The gain of methanol vapor is investigated at various pumping power densities. The behavior of the gain can be described by the four-level rate equation model if the power broadening of the transitions is taken into account phenomenologically. This phenomenologically modified rate equation model reflects the most important features of the density matrix calculations, and it also takes into account the vibrational relaxation, which is not considered in the three-level density matrix calculations. In such a way the pressure behavior of the far-infrared laser is explained by the power broadening of the gain in contrast to the usual explanation relating to the diffusion of the laser molecules.<
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