Spatial-temporal wave mixing for space-time conversion

A nonlinear optical processor that is capable of true real-time conversion of spatial-domain images to ultrafast time-domain optical waveforms is pres ented. The method is based on four-wave mixing between the optical waves of spectrally decomposed ultrashort pulses and spatially Fourier-transformed quasi-monochromatic images. To achieve efficient wave mixing at a femtoseco nd rate we utilize a cascaded second-order nonlinearity arrangement in a be ta-barium berate crystal with type II phase matching. We use this ultrafast technique to experimentally generate several complex-amplitude temporal wa veforms, with efficiency as high as 10%, by virtue of the cascaded nonlinea rity arrangement. (C) 1999 Optical Society of America.