Large third-order optical nonlinearity in BaTiO3 matrix-embedded metal nanoparticles

Composite films consisting of nanoscale Au particles uniformly embedded in barium titanate (BaTiO3) matrices (Au:BaTiO3) were prepared by alternate ablation of metallic Au and ceramic BaTiO3 targets using pulsed laser deposition (PLD) technique. Average diameters of the Au particles were in the range of 2–3 nm. The third-order optical nonlinearity of the composite films was investigated using the 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 (m/W) were determined to be −2.42×10−6 esu and 2.22×10−6 m/W, respectively.