Analysis of the optical response of reptile tissues in the visible and UV applying the KKR method

Abstract

Structural colors in nature are frequently produced by the ordered arrangement ofnanoparticles. Interesting examples include reptiles and birds utilizing lattice-like formation ofnanoparticles to produce a variety of colors. A famous example is the panther chameleon whichis even able to change its color by actively varying the distance between guanine nanocrystalsin its skin. Here, we demonstrate that the application of rigorous electromagnetic methods isimportant to determine the actual optical response of such biological systems. By applying theKorringa-Kohn-Rostoker (KKR) method we calculate the efficiencies of the reflected diffractionorders that can be viewed from directions other than the specular. Our results reveal that importantcharacteristics of the reflectance spectra, especially within the ultraviolet (UV) and short visiblewavelengths region, cannot be predicted by approximate models like the often-applied Maxwell-Garnett approach. Additionally, we show that the KKR method can be employed for the designof multi-layer structures with a desired optical response in the UV regime.