The nanoscale crystals ͑NCs͒ of ZnO were embedded into polymethylmethacrylate ͑PMMA͒ polymeric matrix and nanocomposite films were prepared by modified spin coating method. The surface of the ZnO/PMMA nanocomposite films has been investigated using atomic force and scanning electron microscopy. The prepared films are highly transparent, the ultraviolet-visible spectra show their high optical quality. The second and third harmonic generation ͑SHG and THG͒ studies of ZnO/PMMA nanocomposite films with different concentrations of ZnO NCs were carried out at = 1.064 m and the effective values of the second and third order nonlinear susceptibilities were estimated to be higher than that of ZnO bulk for the films at low concentration of ZnO NCs. This could indicate that surface effects in ZnO/PMMA nanocomposite films have a dominant role over bulk effects for the SHG and THG processes.

We have found that Ru derivative chromophores incorporated into the PMMA polymer matrices might be considered as promising materials for optical poling. The maximally achieved effective second-order optical susceptibility for the wavelength 1.89 µm is about 1.94 pm/V. The investigated composites possess metastable trapping levels originating both from the d states of Ru and due to effective charge transfer due to the presence of π-conjugated states. Because of incorporation of the chromophore into polymer matrices, we have revealed that the maximal susceptibility is observed at 5-6% of the chromophore in weighting units. The further increase of the second-order susceptibility is limited by the appearance of chromophore agglomerates substantially restraining second-order susceptibilities. The investigated composites possess long-lived (2) grating, which decreases less than 76% after 600 min of laser treatment. The electrostatic field causes additional reanimation of the second harmonic generation during the decay regime. The electron microscopy pictures clearly confirm appearance of the (2) grating.

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