Mishchenko Michael I, Dlugach Zhanna M, Zakharova Nadezhda T
Opt Lett. 2014 Jul 1;39(13):3935-8. doi: 10.1364/OL.39.003935.
The modified unrestricted effective-medium refractive index is defined as one that yields accurate values of a representative set of far-field scattering characteristics (including the scattering matrix) for an object made of randomly heterogeneous materials. We validate the concept of the modified unrestricted effective-medium refractive index by comparing numerically exact superposition T-matrix results for a spherical host randomly filled with a large number of identical small inclusions and Lorenz-Mie results for a homogeneous spherical counterpart. A remarkable quantitative agreement between the superposition T-matrix and Lorenz-Mie scattering matrices over the entire range of scattering angles demonstrates unequivocally that the modified unrestricted effective-medium refractive index is a sound (albeit still phenomenological) concept provided that the size parameter of the inclusions is sufficiently small and their number is sufficiently large. Furthermore, it appears that in cases when the concept of the modified unrestricted effective-medium refractive index works, its actual value is close to that predicted by the Maxwell-Garnett mixing rule.
修正的无限制有效介质折射率被定义为这样一种折射率，它能为随机非均匀材料制成的物体给出一组具有代表性的远场散射特性（包括散射矩阵）的精确值。我们通过比较随机填充大量相同小内含物的球形主体的数值精确叠加T矩阵结果和均匀球形对应物的洛伦兹 - 米氏结果，来验证修正的无限制有效介质折射率的概念。在整个散射角范围内，叠加T矩阵和洛伦兹 - 米氏散射矩阵之间显著的定量一致性明确表明，只要内含物的尺寸参数足够小且数量足够大，修正的无限制有效介质折射率就是一个合理的（尽管仍然是唯象的）概念。此外，似乎在修正的无限制有效介质折射率概念起作用的情况下，其实际值接近麦克斯韦 - 加尼特混合规则所预测的值。
