Effect of heavy metals (Ni, Cu, Pb) doped ZnO on the nonlinear optical properties

In this paper, the non-linear optical properties of undoped and doped ZnO thin films were investigated. The films were doped with Ni, Pb, and Cu. an increase in the refractive index against wavelength is apparent for all films up to a certain value of wavelength. Z scan technique is used for measuring the nonlinear optical parameters via open and closed aperture configurations. Third order nonlinear susceptibilities ( χ (3) ) of samples were calculated. The sign of nonlinear refractive index (n 2 ) of ZnO was changed from positive (self-focus) to negative (de-focus) upon metal doping. Doping ZnO with heavy metals changes the sign of nonlinearity although the nonlinear absorption coefficient ( β ) is positive for all samples; the doped materials behave as optical limiters at high intensity. These materials are promising for optoelectronic devices and optical limiting applications.