Saito Akira, Yonezawa Masaru, Murase Junichi, Juodkazis Saulius, Mizeikis Vygantas, Akai-Kasaya Megumi, Kuwahara Yuji
Department of Precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
J Nanosci Nanotechnol. 2011 Apr;11(4):2785-92. doi: 10.1166/jnn.2011.3906.
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.
闪蝶的蓝色具有异常低的角度依赖性，尽管其颜色是基于干涉效应产生特定波长的光。闪蝶独特颜色机制的关键被认为是其鳞片的随机性。利用时域有限差分（FDTD）分析，研究了闪蝶鳞片结构中不同类型随机性所起的作用，而这是传统解析计算无法做到的。结果表明，入射光的非相干性起着至关重要的作用，这仅靠结构随机性是无法实现的。另一方面，发现横向和纵向随机性以及随机成分的数量各自都具有独立作用，以实现闪蝶独特的颜色，防止反射角度依赖性过强。通过数值模拟获得的用于分析光学复杂随机结构的方向，不仅有助于理解科学原理，还能用于设计人造材料的光学特性。
