ANISOTROPIC EFFECTIVE-MEDIUM THEORIES

The optical properties of anisotropic inhomogeneous media are studied within the framework of the classical 3D effective medium theories of Maxwell Garnett and Bruggeman, and the 2D theory of Yamaguchi et al. T he origin of the anisotropy is either the nonspherical shape of the me tallic inclusions in the 3D systems, or the distribution of the inclus ions (even if spherical) on a substrate in the 2D configuration. In bo th cases, it leads to an anisotropic effective medium. In this paper, it is shown that this surrounding anisotropic medium induces a fictiti ous deformation of the inclusions which reduces the anisotropy and shi fts the resonance wavelengths toward the sphere plasmon resonance. In the case of the mean field theory of Bruggeman, it also affects the pe rcolation threshold value. Although some of these theories are now qui te old, they are still extensively used, especially for the prediction s of the absorption of the composite media. Therefore the effect prese nted here for the first time should be taken into account.