Transient energy transfer accompanying the interaction of two collinear beams in resonant media

An experimental investigation was made of the spectral dependences of the gain of a signal beam in the presence of transient frequency-degenerate collinear two-beam interaction in sodium vapor, for the purposes of elucidating the characteristic features of two-beam energy transfer in resonant media. A comparison of the experimental data with the results of a theoretical analysis made it possible to relate the low gain of the signal beam gain to the small energy-transfer contribution of diffraction by the phase component of a dynamic grating and the practically equal contribution of diffraction by its amplitude component.