Enhanced optical nonlinear absorption of graded Au--TiO2 composite films

doi:10.1088/1674-1056/17/6/038

Abstract

Abstract This paper reports that single-layer and graded Au--TiO

_{2}

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

β_{e f f}

of single-layer Au--TiO

_{2}

films is measured to be --2.3

\times

10

^{3} -

0.76

\times

10

^{3}

cm/GW with Au atom content 15%--66%. The

β_{e f f}

value of the 10-layer Au--TiO

_{2}

graded film is enhanced to be --2.1

\times

10

^{4}

cm/GW calculated from p-polarized

Z

-scans, which is about ten times the maximum

β_{e f f}

of single-layer films. Broadened response in the wavelength region 730--860 nm of the enhanced optical nonlinearity of graded Au--TiO

_{2}

composite films was also investigated.

Keywords: Au--TiO

_{2}

granular composites graded composite films

Z

-scan optical nonlinear absorption

Received: 22 October 2007
Revised: 16 November 2007
Accepted manuscript online:

PACS:	78.20.Ci	(Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity))
	42.65.An	(Optical susceptibility, hyperpolarizability)
	42.65.Re	(Ultrafast processes; optical pulse generation and pulse compression)
	78.66.-w	(Optical properties of specific thin films)

Fund: Project supported by the National Natural Science Foundation of China (Grant No 10474075).

Cite this article:

Liu Li(刘莉) and Su Xiong-Rui(苏雄睿) Enhanced optical nonlinear absorption of graded Au--TiO₂ composite films 2008 Chin. Phys. B 17 2170

[1]	Nonlinear optical properties of [(CH₃)₄N]Au(dmit)₂ using Z-scan technique Sun Xiang-Bing(孙香冰), Ren Quan(任诠), Wang Xin-Qiang(王新强), Zhang Guang-Hui(张光辉), Yang Hong-Liang(杨洪亮), Feng Lin(冯林), Xu Dong(许东), and Liu Zhi-Bo(刘智波). Chin. Phys. B, 2006, 15(11): 2618-2622.

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Enhanced optical nonlinear absorption of graded Au--TiO₂ composite films