Scaling properties of optical reflectance from quasi-periodic superlattices

The scaling properties of the optical reflectance from two types of quasi-periodic metal- insulator superlattices, one with the structure of Cantor bars and the other with the structure of Cantorian-Fibonaccian train, have been studied for the region of s-polarized soft x-rays and extreme ultraviolet. By using the hydrodynamic model of electron dynamics and transfer- matrix method, and by taking into account retardation effects, we have presented the formalism of the reflectivity for the superlattices. From our numerical results, we found that the reflection spectra of the quasi-superlattices have a rich structure of self-similarity. The interesting scaling indices of the spectra, which are related to the fractal dimensions, are also discussed for the two kinds of the quasi-superlattices.