a

Nitrogen-doped graphene oxide N-GO nanocomposite synthesized by a hydrothermal method in which urea used as a reduction agent. The reduction of graphene oxide confirmed by the x-ray diffraction, scanning electron microscopy, fourier transform infrared and UV-VIS spectroscopy analyzes. The measurement of the distance between the sheets and energy band gap of the N-GO nanocomposite indicated an increasing in interspaces of sheets and a slight broadening in energy band gap due to adding of nitrogen. For the first time, the optical susceptibility of N-GO nanocomposite calculated via Z-scan technique and confirmed the third-order optical nonlinearity. The nonlinear optical susceptibility calculated in the order of 10-9 esu that shows the high efficiency of this nanocomposite for using in optoelectronic devices.