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. This 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 duration of ultrashort light pulses at their fundamental frequency with intensities less than a few GW/cm2.