Phase Conjugate Reflection Of Electromagnetic Waves From A Plasma

The following paper reports on the possibility of using a plasma, as the nonlinear medium, for generating phase conjugate reflection of electromagnetic waves in the microwave region, by almost degenerate four wave mixing. The reflected beam can be significantly amplified by the plasma. We show that the phase conjugate reflection is of significant magnitude if the frequency and the wave vector difference of the signal wave, with respect to the pump waves, resonate with the frequency and the wave vector of the ion acoustic mode of the plasma. This resonance can be predicted from a fluid like description of the plasma, but the Vlasov description can provide more details of the behavior near the resonance. The main results of the theory developed are described, as well as the experimental set-up we are currently building to verify the phase conjugation. Possible applications of the emergent technology are discussed.