Synthesis and characterization of linear/nonlinear optical properties of graphene oxide and reduced graphene...

In this paper, we aimed to investigate the linear and nonlinear optical properties of GO-ZnO and RGO-ZnO nanocomposites in comparison with pure GO and reduced graphene oxide (RGO). For this purpose, GO, RGO, GO-ZnO, and RGO-ZnO were synthesized and characterized by Fourier transform infrared (FT-IR), Ultraviolet-Visible (UV-Vis) absorption, X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). XRD and EDX analysis indicated the reduction of GO as well as the successful synthesis of GO-ZnO and RGO-ZnO nanocomposites. The FT-IR spectroscopy showed that absorption bands were at 3340 cm^-1, 1630 cm^-1, 1730 cm^-1 and 480 cm^-1 related to OH, C=C, C=O, and Zn-O stretching vibrations, respectively. The direct band gaps of GO, RGO, GO-ZnO and RGO-ZnO from UV-Vis spectra were at 3.36, 3.18, 3.63 and 3.25 eV, sequentially. Moreover, the third-order nonlinear optical properties were investigated using a z-scan technique with Nd: YAG laser (532 nm, 70 mW). It can be seen that the nonlinear absorption coefficient value [Formula: see text] increased from 5.3 × 10^-4 (GO) to 8.4 × 10^-3 cm/W (RGO-ZnO). In addition, nonlinear refractive index (n₂) of the GO, RGO, GO-ZnO, and RGO-ZnO was obtained as 10.9 × 10^-10, 14.3 × 10^-10, 22.9 × 10^-10, and 31.9 × 10^-10 cm²/W respectively.