Nondegenerate reversal of polarized light by four-wave interaction in a resonant medium

The representation of irreducible tensor operators is used to develop a theory of wavefront reversal (WFR) in the absence of saturation effects. This theory deals with arbitrarily polarized waves in a two-level resonant medium having arbitrary angular momenta. It is shown that there are three different physical reversal mechanisms associated with a nonuniform population and with the coherence of the magnetic sublevels in the field. An investigation is made of the influence of the decay times of the polarization moments of the system (the total population, orientation, alignment) on WFR. In particular, it is shown that, subject to specific relationships between the decay times, new collision-induced reversal processes can occur in the presence of deorienting collisions. An investigation is made of the spectral composition of the reflection coefficient of the reversed wave and it is shown that there are various spectral ranges of efficient reversal which in general depend on the polarizations of the interacting waves.