Theoretical approaches to study the optical response of the red-legged honeycreeper?s plumage (Cyanerpes cyaneus)

GONZALO M. URQUIA; MARINA E. INCHAUSSANDAGUE; DIANA C. SKIGIN; MARCELO LESTER; ANA BARREIRA; PABLO TUBARO

APPLIED OPTICS

OPTICAL SOC AMER

Lugar: Washington; Año: 2020 vol. 59 p. 3901 - 3909

0003-6935

In this paper, we investigate the unusual color effect exhibited by the plumage of the heads of Cyanerpes cyaneus males, whose color turns from green to turquoise as the angle between the illumination and observation directionsis increased. This singular color effect is characteristic of species that have quasi-ordered nanostructures of shortrange order within the feather barbs. However, among species of the same family and even within feather patchesof the same individual, one can find barbs with different characteristics, both macroscopic (curvature, shape, cross-sectional area) and in their internal microstructure.We apply the Korringa?Kohn?Rostoker method with theaveraging technique to model the reflectance spectra for different angles of incidence and explain the dependenc of the observed color with the incidence-collection angle. To investigate the influence of the disorder in the opticalresponse of the spongy matrix, we apply the integral method for a two-dimensional cylinder system that simulates the distribution of air cavities within the β-keratin medium. The experimental reflectance was interpreted as theresult of multiple reflections in the internal interfaces generated by large air voids present within thespongy matrix. The application of rigorous methods to the study of natural photonic structures is of fundamental relevance for thedesign of efficient bioinspired artificial materials.