Graphene oxide induced the enhancement of nonlinear optical response of ITO films

The indium tin oxide-graphene oxide (ITO/GO) composite films with different thickness of GO for a mixed ITO thickness was synthesized by a facile solid-liquid thermal recombination. The structure and the optical properties of ITO/GO composites were analyzed by X-ray diffraction (XRD), Raman spectra, ellipsometer and the UV-VIS-NIR double beam spectrophotometer. The nonlinear optical properties of specimen were successfully investigated by a single Z-scan technique. The experimental results showed that the epsilon-near-zero (ENZ) wavelength of composites can be tuned from 1225 to 1940 nm by adjusting the thickness of GO. The nonlinear absorption coefficient (β=−4.0×108 cm/GW) for composites is about 1.8 times greater than that of the single-layer ITO films. Additionally, the results of Finite-Difference Time-Domain (FDTD) are in good agreement with those of the experiments. [Display omitted] •The nonlinear absorption coefficient for ITO composite materials with a little GO is about 1.8 times greater than that of single layer ITO films.•The tunable Epsilon-Near-Zero ITO films with the range from 1225 to 1940 nm were obtained by adjusting the thickness of GO.•Graphene oxide induced defects driving the special optical characteristics of ITO films was confirmed by Raman scattering spectra.•The simulation results of FDTD regarding the electric field distribution of samples are consistent with those of experiments.