中文摘要：

利用退耦近似方法，数值研究了任意体积分数特别是高体积分数的金属颗粒复合介质膜的有效线性介电函数和三阶非线性效应的变化，得到了非线性增强的最佳体积比。在不同体积分数下研究了复合体系的三阶非线性效应随入射光频率的变化关系，结果表明在表面等离子体共振频率附近，三阶非线性效应随着体积分数的增加而增强，但是当体积分数增加到一定值时由于粒子之间的相互作用对局域场的影响导致了三阶非线性效应的降低。

英文摘要：

The nonlinear decoupling approximation is used to calculate numerically the effective linear dielectric function and third order nonlinear effect of metal particle composite media as function of random volume fraction, especially the high volume fraction, which show the nonlinear optimum volume ratio. The optical nonlinearity of composite media as functions of the frequency of the incident light under different volume fraction have been studied. It is found that near the surface plasmon resonance, optical nonlinearity increases when volume fraction inereases to certain value and then decrease due to the influence of the particle-particle interaction to the local field.