title: Numerical analysis on the optical role of nano-randomness on the Morpho butterfly's scale.
abstract: The blue coloration of Morpho butterflies has anomalously low angular dependence despite the production of color with a selected wavelength based on an interference effect. A key to the mechanism of the specific Morpho-color was suggested to be the randomness of its scale. Using finite-difference time-domain (FDTD) analysis, the role of different kinds of randomness in the structure of the Morpho butterfly's scale was investigated, which was impossible by conventional analytical calculations. The results revealed that incoherence in the incident light plays an essential role, which cannot be realized only by structural randomness. On the other hand, the lateral and vertical randomness, and the number of random components were found each to have an independent role to realize the specific Morpho-color preventing the sharp reflective angular dependence. The direction obtained by the numerical simulations to analyze optically complex random structures will serve not only to understand the scientific principles, but also to design the optical properties of artificial materials.
authors.affiliation: Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Saito
authors.forename: Masaru
authors.initials: M
authors.lastname: Yonezawa
authors.forename: Junichi
authors.initials: J
authors.lastname: Murase
authors.forename: Saulius
authors.initials: S
authors.lastname: Juodkazis
authors.forename: Vygantas
authors.initials: V
authors.lastname: Mizeikis
authors.forename: Megumi
authors.initials: M
authors.lastname: Akai-Kasaya
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kuwahara
mesh_terms: D000818:Animals; D002080:Butterflies / Q000737:chemistry* / Q000502:physiology*; D003116:Color; D003198:Computer Simulation; D008027:Light; D008954:Models, Biological; D008956:Models, Chemical; D012031:Refractometry; D012542:Scattering, Radiation