Optical characterization of iridescent wings of butterflies usingmultilayer rigorous coupled wave analysis

摘要

In certain species of moths and butterflies iridescent colors arise from sub-wavelength diffractive surface corrugation ofthe wing-scales. The optical properties of such structures depend strongly on the wavelength, the incidence angle, thepolarization of illuminating radiation, and the index of ambient medium. In this paper, after getting the SEM picture ofthe dorsal scales of the Morpho didius butterfly, we construct a bionic two dimension model, whose ridge contains acertain quasi-periodic arrangement of tree-like sub-wavelength microstructures. Then using a multilayer rigorouscoupled wave analysis method in two dimensions, we study the reflection spectra of the wings of Morpho didiusbutterfly by simulating the multilayer model of a transverse cross-section comprised of the ground scale. Here weassume that the structure is made of a slightly lossy dielectric material and analyzed the polarization, the incidence angleand the index of ambient medium which affect the reflection spectra strongly. The results got, have revealed the naturalphenomenon of iridescent colors and color-changed in essence, and the simulation results enable an artificial micro-sensor which discriminate vapor or component by reflective efficiency spectra.