Suppression of fluctuations of the intensity of harmonics in resonant frequency multiplication

An investigation is made of fluctuations of the intensities of optical harmonics generated under resonant conditions by the field of randomly modulated pump radiation. An experimental study is reported of the dependence of the relative variance of the intensity of the third harmonic on the average pump radiation intensity under conditions of a three-photon resonance involving the 3s –5p transition in sodium vapor. The results indicated the possibility of suppressing fluctuations of the harmonic intensity under saturation conditions. A theory explaining this suppression effect is put forward.