Résumé
Novel non-linear optical polymeric film-producing nanocomposites based on bis(arene)chromium complexes incorporated into CN-containing matrices have been developed. Measurements by the spectrally resolved two-beam coupling method with a femtosecond range of pulse widths (central wavelength 795-800 nm) confirmed that the test composites exhibited a significant cubic nonlinear optical susceptibility of the ultra-fast electronic type. An open aperture Z-scan of the polymer film at 1550 nm showed a value of 9 × 10¿19 cm3 W¿2 for the three-photon absorption coefficient. The electro-optical measurements of the polymer composite showed a high electro-optical response (r33.n3 = 4.245 pm V¿1 at modulation frequency 210 Hz and poling DC voltage 2.16 V). A significant enhancement of the signals with a decrease in modulation frequency was observed consistent with an essential contribution of orientation effects to the electro-optical response. The measurements in the absence of external electrical fields showed a natural anisotropy resulting from self-organization taking place during the film formation process as confirmed by electron diffraction studies. A single Cr-C distance was found in the EXAFS data refinement, showing that the arene rings are parallel and symmetric as in bis(benzene) chromium.