Laser beam shape and curvature radius of the laser wavefront passing through ZnO nanostructures

In the present work, we focus on synthesis and optical properties of ZnO nanostructures prepared by the chemical vapour deposition method. The nonlinear optical properties of ZnO nanostructures in ethanol solution were studied by the Z-scan technique using CW He-Ne laser at 632.8 nm. The results show a negative nonlinearity and a large nonlinear refractive index. The magnitude and the sign of nonlinear refractive index, n(2), were measured using the single beam Z-scan technique. The effect of morphology on nonlinear optical properties of ZnO nanowires is investigated. The laser beam shape and variation of the curvature radius of the wavefront have been simulated when the Gaussian laser beam passes through ZnO nanowires in ethanol. The effect of concentration is investigated in the nonlinearity. We have reported the curvature radius of the wavefront to the nonlinearity for ZnO nanowires as nonlinear sample. Also we found good agreement between the results of theoretical laser beam shape passing through ZnO nanostructure and the experimental data. (C) 2010 Elsevier B.V. All rights reserved.