Design of a structure with low incident and viewing angle dependence inspired by Morpho butterflies

Morpho butterflies are well known for their brilliant iridescent colors, which arise from periodic arrays of scales. These brilliant colors have a low angle dependence, in contrast to similar phenomena that are commonly caused by the periodic structures. We designed a structure with a low incident and viewing angle dependence inspired by Morpho butterflies. This structure was studied using the finite-difference time-domain method. The lamellae distribution of tree-like structure was found to be the determining factor for producing a low incident angle dependence. Two advanced models were designed to produce a low viewing angle dependence. Model I was constructed using two layers of scales. The particle swarm optimization algorithm was used to construct Model II. The angle dependence of Model II exhibited a large viewing angle range under various incident angles.