Demonstration of Degenerate Four Wave Mixing and Phase Conjugation of CO₂ Laser in a Plasma

Abstract

Experimental evidence of degenerate four wave mixing in a plasma is presented for the first time. A thermal-force contribution to the signal reflectivity, as evidenced by its temporal shape and dependence on plasma density, pump and probe intensities, and polarizations dominates that due to the ponderomotive force in a collisional plasma. In SF₆ gas, two pump-probe gratings contribute almost equally to the reflectivity. It is also found that ion acoustic resonance can enhance the phase conjugate reflectivity in the plasma.