Modeling of anisotropic optical properties of ordered cluster-dot structures

To develop ordered cluster-dot structures with predetermined optical properties a model which self-consistently allows to define an electrical field induced by a propagating electromagnetic wave has been elaborated. The model takes into account the contribution of two kinds of anisotropy: the anisotropy of the polarizability of the clusters (`shape anisotropy'), and the anisotropy of their dipole interaction (`structure anisotropy') determined by the anisotropy of the spatial arrangement of the cluster-dots. By numerical computer calculations the components of the tensor of dipole sums versus the degree of structural anisotropy were determined, and it was shown that both types of anisotropy can have the same order of magnitude. Depending on the geometrical configuration of the dot-system, the shape and structure anisotropy can compete or corroborate with one another causing an increase or decrease of the local electric field anisotropy, and thus lead to a change of the anisotropy of the refractive index and of the extinction coefficient of the structure. Strong artificial birefringence, as well as the modifications of the optical absorption spectra predicted by the model are discussed and compared with experiment.