Polarization characteristics of a noncoplanar concurrent four-wave interaction in resonant media

An analysis is made of a noncoplanar concurrent four-wave interaction in the field of linearly polarized pump waves in resonant media modeled by linear (or circular) dipoles. The parametric gain increments and the polarization of weak radiation are determined, in the cubic approximation, as a function of the polarization characteristics of the waves being mixed and of the properties of the resonant medium. In the case of orthogonally polarized pump waves the polarization of the signal is conserved irrespective of the model adopted for a resonant medium and the polarization of a diffracted wave is "reversed" relative to the signal. In the case of parallel orientation of the pump wave vectors the polarization of a linearly polarized signal is retained if the vector of its amplitude is oriented parallel or orthogonal to the pump waves. In a medium modeled by an ensemble of randomly oriented dipoles when the angle between the pump wave vectors is 2π/3 or π/3 the radiation is linearly polarized irrespective of the polarization structure of the input signal.