Enhancement of nonlinear optical properties of Au-TiO2granular composite with high percolation threshold

✍ Scribed by Zhou, Z. K. ;Li, M. ;Su, X. R. ;Zhai, Y. Y. ;Song, H. ;Han, J. B. ;Hao, Z. H.

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 406 KB
• Volume: 205
• Category: Article
• ISSN: 0031-8965
• DOI: 10.1002/pssa.200723293

✦ Synopsis

Abstract

Two series of Au–TiO~2~ composite films with Au percola‐ tion threshold q~C~ of 0.34 and 0.82 were prepared by using sputtering technique at the pressure of 5.0 × 10^–2^ and 8.0 × 10^–2^ Torr, respectively. As q~C~ increases from 0.34 to 0.82, the plasmon resonant absorption of the composite films near q~C~ shifts from about 700 nm to 760 nm, and the maximal second harmonic generation (SHG) intensity increases by 20%, the maximal nonlinear absorption coefficient increases from –3.0 × 10^4^ cm/GW to 1.7 × 10^5^ cm/GW, and the maximal nonlinear refraction index increases from a very small value to –2.6 cm^2^/GW. The large second‐ and third‐order optical nonlinearity of the Au–TiO~2~ composite films with high q~C~ is attributed to the high density of Au particle in the nonconductive film and the strong local field enhancement caused by the surface plasmon resonant absorption. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)