Color generation in butterfly wings and fabrication of such structures

The wings of the morpho butterfly demonstrate an iridescent blue color over wide viewing angles. The mechanism that generates this blue color is studied. Optical and transmission electron microscopy of the butterfly wings reveal a complex wing structure with as many as 24 layers with periodic structures. The color generation is caused by interference of the multilayer structure as well as diffraction. It is possible to specially design grating structures so that a specific blue color can be generated and observed over wider angles. To demonstrate the grating concept, complex multigratings are designed and fabricated with electron-beam lithography. The light-diffraction properties of these gratings are presented.