Absence of circular polarisation in reflections of butterfly wing scales with chiral gyroid structure

摘要: The single Gyroid, a triply-periodic ordered chiral network of cubic symmetry, appears as nanostructure in the green-colored wing scales various butterflies. In lossless and perfectly Gyroid materials, structural chirality leads to circularly polarized reflections from crystals oriented [100] direction. Here we report circular polarisation study macroscopic Callophrys rubi Teinopalpus imperialis that reveals no dichroism, is, find significant difference reflectance values for left- right-circularly light. reasons absence is likely be compound effect factors, including crystallite orientation, presence both right-handed enantiomers, disorder. Each these factors weakens, but does not fully extinguish, signal. We further substantial amount blue-absorbing pigment those C. are structured according Gyroid. Numerical simulations demonstrate absorption, while evidently reducing overall reflectance, generally reduce dichroism strength. experimental findings this paper, however, clearly absent butterfly scale. Henceforth, chiro-optical response idealised structure fulfil biological photonic function.