Refractive non-linearity in double-sided nanosize films containing methanofullerene derivative fabricated by electrostatic self-assembly technique

The non-linear optical properties of the double-sided nanosize films containing a methanofullerene derivative and its solution were investigated by Z-scan technique with an 8 ns, 532 nm Nd:YAG laser system. The films were fabricated using the electrostatic layer-by-layer self-assembly technique. The materials contained a positively charged trifluoroacetic acid salt of triamino-substitute methanofullerene derivative and a negatively charged poly (sodium 4-styrenesulfonate). The 20-bilayer film shows strong self-defocusing effect with a non-linear refractive index n2 of −7.0 × 10−6 esu, which was extracted from the experimental data based on the Huygens-Fresnel diffraction integral. On the other hand, the solution exhibits great reverse saturation absorption effect.