The third-order nonlinear optical response of Au nanocrystals embedded in BaTiO3 and ZrO2 matrices were investigated by off-resonance femtosecond optical Kerr effect. The nonlinearity of composite films show an enhancement comparing with the pristine matrices films, which is Au particle size and matrices refractive index dependence. A calculation based on Lorenz-Mie scattering theory was performed to explain the experimental results. Additionally, optimization of nonlinearity was obtained by considering the particle size and matrices refractive index.
By using two-color femtosecond optically heterodyned optical Kerr effect experiment, we studied the real components of third-order nonlinearity of 2,5-dioctyloxy poly(p-phenylene vinylene) (DO-PPV). As pump wavelength was set near the absorption region of the material, the value of x(3) of DO-PPV was improved by one order of the magnitude comparing with that of nonresonant condition. We suggest that this enhancement result from the contribution of the excited state.
In this paper, we report the photoconductivity property of different poly (p-phenylene vinylene) (PPV)/C60 composite films fabricated by physical jet deposition technique. The results indicate that the photoconductive enhancement effect in PPV/C60 composite films depends on the different charge transfer efficiency at the interface between PPV derivatives and C60. The wavelength dependence and temporal evolution of photoconductivity of composite films were also measured in our experiments, and it was found that some PPV/C60 composite films showed quite better photoresponse and stability. It can be expected that the conjugated polymer/fullerene composite film optimized by an appropriate configuration have the potential application in thin-film photoelectric devices.
By using the femtosecond optically heterodyned optical Kerr effect at 647.0 nm we have measured the magnitudes and signs of the real components of third-order nonlinearity of organometallic compounds films of C60M2 fabricated through a series of reactions of C60 anions with some inorganic compound in solution phase and physical jet deposition technique. We find there is an enhancement of the real components of third-order optical nonlinearities of C60M2 films compared to that of pristine C60 film, which can be attributed to the charge transfer from metal atoms to C60 molecules. The signs of the real components of third-order optical nonlinearity of C60 and C60$M(subscript 2 films are negative. We also find the disposition temperature will affect third-order optical nonlinearities of C60M2 films.
MBB-PPV/C60 and MB-PPV/C60 composite films were fabricated by physical jet deposition technique and the effect of the film structure and the polymer on the photoconductivity of composite film were studied. Both composite films show the enhancement of the photoconductivity over the pure PPV and C60 while the enhancement of the photoconductivity of MBB-PPV/C60 film was found better than that of MB-PPV/C60 due to more efficient excitation transfer and charge transfer properties in MBB-PPV/C60 multilayer film. The result of time- resolved photoluminescence further confirms the high efficiency of charge transfer process occurring at the interface between MBB-PPV and C60 layers in the composite film.
We have fabricated thin film of the star-like C60(CH3)x(PAN)x copolymer. Optical property and ultrafast nonlinear optical response of the copolymer films were measured. The absorption and photoluminescence spectra showed the intramolecular excitation transfer process existed in the copolymer. From the femtosecond optical Kerr effect measurement, third-order nonlinear optical susceptibility of the copolymer film was found bigger than that of pure PAN and fullerene molecule which result from a new lower excited state and the redistribution of the electron cloud in the copolymer.