Optical function of the finite-thickness corrugated pellicle of euglenoids

Electromagnetic response of corrugated multilayer systems inspired by the Dione vanillae butterfly scales

Inspired by the microstructures in the wing scales of the butterfly Dione vanillae, we investigate the optical response of two multilayer structures, which include one or two corrugated interfaces. The reflectance is calculated using the C-method and is compared with that of a planar multilayer. We perform a detailed analysis of the influence of each geometric parameter and study the angular response, which is important for structures exhibiting iridescence. The results of this study aim to contribute to the design of multilayer structures with predetermined optical responses.

Analysis of the optical properties of the silvery spots on the wings of the Gulf Fritillary, Dione vanillae

The ventral face of the wings of the butterfly Dione vanillae is covered with bright and shiny silvery spots. These areas contain densely packed ground- and coverscales with a bright metallic appearance reflecting more than 50% of light uniformly over the visible range. Our analysis shows that this optically attractive feature is caused by the inner microstructure of the scales located in these areas. Electron microscopy of cross sections through the scales shows that upper and lower lamina, supporting trabeculae, and topping ridges can be approximated by a 'circus tent'-like geometry. By simulating its optical properties, we show that a moderate disorder of this geometry is important for the uniform reflection of light resulting in the silvery appearance.

Rayleigh method adapted for the study of the optical response of natural photonic structures

To study the electromagnetic response of natural structures that exhibit interesting optical properties, we developed a computational tool to solve the problem of electromagnetic scattering by a rough interface between two isotropic media, based on the Rayleigh method. The key aspect of the developed formalism is its capability of introducing the interface profile within the code by means of a digitalized image of the structure, which can be either obtained from an electron microscopy image or simply by design according to the complexity of the scattering surface. As application examples, we show the results obtained for surfaces taken directly from microscopy images of two different biological species. This approach constitutes a fundamental step in order to model the electromagnetic response of natural photonic structures.