Enhanced optical nonlinear absorption of graded Au-TiO2 composite films

• 来源期刊: 中国物理B(英文版)
• 关键词: Au-TiO2 granular composites graded composite films Z-scan optical nonlinear absorption
• 年，卷（期）: 2008,（6）
• 页码范围: 2170-2174
• 页数: 5页
• 语种: 英文

摘要

This paper reports that single-layer and graded Au-TiO2 granular composite films with Au atom content 15%- 66% were prepared by using reactive co-sputtering technique. The third-order optical nonlinearity of single-layer and graded composite films was investigated by using s- and p-polarized Z-scans in femtosecond time scale. The nonlinear absorption coefficient βeff of single-layer Au-TiO2 films is measured to be -2.3 x 103-0.76 x 103 cm/GW with Au atom content 15%-66%. The βeff value of the 10-layer Au-TiO2 graded film is enhanced to be -2.1×104cm/GW calculated from p-polarized Z-scans, which is about ten times the maximum βeff of single-layer films. Broadened response in the wavelength region 730-860 nm of the enhanced optical nonlinearity of graded Au-TiO2 composite films was also investigated.