Optical characteristics of gold nanoparticle-doped multilayer thin film

A variety of surface plasmon resonance (SPR) peaks of gold nanoparticles was detected in the wavelength range between the SPR peak of Au/SiO2(∼535 nm) and Au/TiO2(∼655 nm) with the parameter x in the triple-component composite films, (SiO2)1−x/Au/(TiO2)x. Based on the spectrum of the dielectric constant of Au and the location of the SPR peaks, the effective refractive index neff of these composite films was found to be almost equal to nSiO2∙(1−x)+n_TiO2∙x. These composite films can be used as optical filters owing to their high damage threshold value (>6.5 MW/cm2). Their potential applications in nonlinear optical devices are due to their larger third-order nonlinear susceptibilities, chi(3), which were measured by the degenerate four-wave-mixing method at a laser wavelength of 532 nm. The chi(3) value reached 2.6×10^−6 esu.