GENERATION OF HIGH-CONTRAST NARROW-BAND SUBPICOSECOND CORRELATIONS FROM BROAD-BAND STOCHASTIC FIELDS

We demonstrate that two broadband stochastic fields generated by use o f either parametric frequency conversion or stimulated Raman scatterin g can be mixed in a nonlinear crystal to produce an output spectrum wi th a pronounced narrow-band feature. This narrow-band feature, which w e show is due to the phase-correlated nature of the beams, is present when the two broadband beams are delayed less than a coherence length relative to each other. We apply this technique to a novel measurement of the field cross-correlation function between two broadband stochas tic fields with different center frequencies.