Influence of basal melanin in the electromagnetic response of regular and weakly disordered photonic crystals

Abstract

Motivated by the structural color generation in the plumage of some species of birds, which in their barbs combine a quasi-regular arrangement of air voids in a keratin matrix (spongy matrix) backed by melanin granules, in this work we study the influence of basal melanin on the optical response of regular and weakly disordered photonic crystals. By applying two rigorous electromagnetic methods, we investigate the effect produced by a basal layer of melanin granules on the reflected response of regular and slightly irregular photonic crystals comprising infinite cylinders (2D) or spheres (3D). The results show that even for a few layers of scatterers, the reflected response is governed by the geometry, distribution and materials comprising the spongy matrix, and is only weakly dependent onthe presence of melanin. This result is found for both 2D and 3D structures, and for finite and infinite systems, indicating a general trend.