Preparation and third-order optical nonlinearity of gold nanoparticles incorporated mesoporous TiO2 thin films

A kind of Au nanoparticle (NP) containing 2D hexagonal mesoporous TiO2 thin films (MTTFs) has been successfully synthesized through a deposition-precipitation method. The Au NPs show uniform size distribution and the Au content within the MTTFs is measured to be 7.49 wt.%. The third-order nonlinear optical refractive index of the Au NPs contained MTTFs has been measured by the Z-scan technique at 1064 urn. The absolute value of nonlinear refractive index (n(2)) and third-order nonlinear susceptibility (chi((3))) were calculated to be 2.64 X 10(-7) and 6.32 X 10(-8) esu, respectively. The high nonlinearity of the composite thin films can be attributed to the intraband transition of electrons near the Fermi surface in well-dispersed An NPs confined in mesoporous channels and the high linear refractive index of the nanocrystalline anatase framework. 0 2008 Optical Society of America