Transient energy transfer between coherent light beams in a resonant medium

Transient conversion of the energy of two coherent light beams in a resonant medium is analyzed by the coupled wave method. It is shown that such conversion has a threshold, is spectrally sensitive, and results in preferential energy transfer from a strong to a weak beam in normal and inverted media. The calculated and experimental energy-conversion intensities are compared for two light beams used to record dynamic holograms in sodium vapor.