Optical nonlinearities of BaTiO3 matrix-embedded Au nanoparticles

Composite thin films Au/BaTiO3 comprising nanometer-sized gold particles embedded in BaTiO3 matrices were synthesized on MgO(1 0 0) substrates by co-depositing Au and BaTiO3 targets using pulsed laser deposition technique. The nanostructure of the films and the size distributions of the Au particles were analyzed by high-resolution transmission electron microscopy. Crystal lattice fringes from the Au nanocrystals and BaTiO3 matrices were observed. The nonlinear optical properties of the Au/BaTiO3 films were measured using z-scan method at the wavelength of 532 nm with a laser duration of 10 ns. The nonlinear refractive index n2 and the nonlinear absorption coefficient β were determined to be 2.72 × 10−6 esu and −1.1 × l0−6 m/W, respectively.