Enhancement of optical nonlinearity in Ag:BaTiO3 composite films by applying an electric field during growth

We prepared the Ag:BaTiO3 composite films by pulsed-laser deposition technique. The films were grown on MgO (100) substrates under a nitrogen pressure of 10.0 Pa at 600°C, and a parallel electric field was applied on the substrate during growth. The chemical natures of Ag in the films were measured by x-ray photoelectron spectroscopy. The linear optical properties of the films were studied in the wavelength range of 330 to 700 nm. The third-order nonlinear optical susceptibilities of the films were determined by z-scan method at the wavelength of 532 nm with a laser duration of 10 ns. The figure of merit (FOM) was ∼1 order of magnitude larger than that of the films that were grown without an electric field and reached 1.62×10^−10 esu cm. Our experimental results have demonstrated that an external electrical field can induce the metal-particle orientation in order and therefore enhances the FOM of the metal-dielectric composite films.