Influence of the laser radiation field on the absorption of pump radiation in a three-level system

A reduction in the absorption of the pump radiation under the influence of the laser radiation field was observed for a pulsed CF₄ laser. The effect was due to two-photon processes and appeared for a small detuning of the radiation frequencies from a resonance. The results of a calculation carried out on the basis of a steady-state three-level model agreed well with the experimental data.