Two-photon photochromism of a photorefractive organic material for holographic recording

We report the two-photon induced photoisomerization of 3-[1-(1,2-dimethyl-1H-indol-3-yl)-ethylidene]-4-isopropylidene-dihydro-furan-2,5-dione (1), a photochromic compound with lambda (max) = 385 mn, using 775 nm fs pulses. The resulting photoisomer has a lambda (max) = 582 nn. The kinectic rate content for the isomerization reaction was measured at two different intensities (two different powers), showing a quadratic dependence with respect to the pump intensity. Results of pump-probe solution phase experiments and guest/host polymer thin film interferometric imaging studies are shown. A two-photon absorption molecular cross-section sigma2=10.3 x 10(-48) cm(4).s/photon was measured using Z-scan, supporting a two-photon induced isomerization process.