Measurement of cross-phase modulation in optical materials through the direct measurement of the optical phase change

We measure the cross-phase modulation (XPM) nonlinear indices of optical materials resulting from the interaction of an ultrashort pump pulse at 800 nm with a weak ultrashort probe pulse at 400 nm through the direct measurement of the optical phase change, using frequency-resolved optical gating. The materials studied include fused silica $\left({\mathrm{SiO}}_2\right)$, borosilicate glass (BK-7), $\beta ‐\mathrm{BBO}$, and ${\mathrm{KD}}^{*}\mathrm{P}$. This method results in a XPM nonlinear index that is in agreement with calculations based on nonlinear indices from previous self-phase modulation measurements.