Linear and nonlinear optical properties of Ag nanocluster/BaTiO3 composite films

To investigate the optical properties of metallic nanocluster/oxide composite films, Ag nanocluster/BaTiO3 composite films were synthesized on MgO (100) substrates by co-depositing the Ag and BaTiO3 targets using pulsed laser deposition. The x-ray diffraction results demonstrated that the Ag and BaTiO3 were well crystallized. The x-ray photoelectron spectroscopy analysis indicated that the samples were composed of nano-metal Ag embedded in the BaTiO3 matrices. The optical absorption properties were measured from 300 to 800 nm, and the absorption peaks due to the surface plasmon resonance of Ag particles were observed. With increasing the Ag concentration, the peak absorption increased and shifted to longer wavelength (redshift). Furthermore, the z-scan results showed that the films exhibited large optical nonlinearities and the signs of the nonlinear absorption (β) and nonlinear refractive index (n2) changed with increasing the Ag concentration.