Frequency pulling in lasers with nonlinear absorption

An experimental investigation was made of the pulling of the stimulated emission frequency by a narrow molecular resonance in lasers with nonlinear absorption cells. An original method was developed for measuring the frequency stabilization coefficient. The basic dependences of the degree of pulling on the intensity of the saturating field, stimulated emission frequency, gas pressure, and transit effects were determined. A theoretical expression was obtained for the pulling of the frequency toward the center of the absorption line. This expression was in good agreement with experiment and was valid in strong saturating fields. The pulling effect was used to determine the principal spectral characteristics of the active molecular transition.