LIGHT-SHIFT-INDUCED SPATIAL STRUCTURES - APPLICATION TO DEGENERATE 4-WAVE-MIXING

Degenerate four-wave mixing in dense sodium vapor under conditions of strong pressure-induced Zeeman pumping is investigated. Thermal diffus ion and its interplay with the Zeeman light shift are found to be resp onsible for the generation of a grating mechanism that is not sensitiv e to thermal washout. The effect can be observed experimentally after eliminating the influence of radiation trapping by the use of nitrogen as a buffer gas. Under these conditions large nonlinearities are prod uced which also influence the propagation of the signal wave via colli sion-aided circular birefringence.