Nonlinear Optics Technology, Area 1: FWM (Four Wave Mixing) Technology

Four wave mixing FWM performance in Na vapor was evaluated in the strong pumping regime IIsat required for typical applications related to point-to-point optical links. Gain reflectivity, imaging fidelity, and noise crosstalk were measured and analyzed under several conditions to obtain an engineering data base for potential tactical applications such as communications, surveillance, and guidance systems. Results include or 230 reflectivity and 15 lines pairmm imaging resolution, both the highest reported to date with cw pumping in low density Na vapor. The observed resolution was limited by the pixel spacing of our video camera. Ten 1pmm resolution was obtained after passing the input image through a 65 lambda aberrator. Noise crosstalk was observable only when the combined signalnoise powers were large enough to saturate the phase conjugate return signal via pump depletion. Under these conditions, a degenerate, coherent noise beam 3x stronger than the signal beam produced only a 21 reduction in the intensity of the phase conjugate signal, and this degree of crosstalk decreased rapidly as the pumpnoise angle increased.