Preparation and nonlinear optical properties of Au/glass composite thin films

Small metal particles embedded in glasses have been widely studied as resonant type third- order nonlinear optical materials for photonic devices. We have prepared Au/SiO2, Au/Al2O3, Au/TiO2 composite thin films by a multitarget sputtering method. The χ(3) and τ of the composite thin films were investigated by means of femtosecond Z-scan and pump-probe experiment, respectively. In the optical-absorption spectra of the three types of the films, the clear absorption peak due to the surface plasmon resonance of Au particles is observed. The imaginary part of χ(3) and τ for the Au/TiO2 film were -3.6 × 10−7 esu and ~2 ps, respectively. The χ(3) of Au/SiO2, Au/Al2O3, AU/tiO2 films increased in that order.