INTERFEROMETRIC DETECTION OF CROSS-PHASE MODULATION IN CDS

Using short 130 fs light pulses in a pump-probe experiment we measured the transmission change under a strong irradiation (almost-equal-to 5 GW/cm2) of a Fabry-Perot-like CdS sample, at room temperature, Using a simple model we deduced a nonlinear index n2 = 5 x 10(-13) cm2/W. Th is index is only due to the electric field effect of the pulse for it is measured in a time shorter than the electronic relaxation time. We show that this experimental method could be used for measuring the dur ation of ultrashort light pulses at their fundamental frequency with i ntensities less than a few GW/cm2.