The butterfly wing and the nanotechnology: structural color

Structural colors are those generated as a result of constructive interference from a diffraction grade or from nanometric ordered structures. The structural color differs from chemical color (found in the majority of living beings) by having no pigments or colorants, but as a result of optical surface effects. The butterfly wings are the best examples of structural color's generator and, with microscopic observations, details of these structures were described and the knowledge of this phenomenon increased. With the advances of the nanotechnology, the first ones artificial replications of these structures were attained with potential application in several technological fields. In this paper the main differences between chemical and structural color, from the physical point of view, are presented by using a quite simple formalism, though sufficient enough to explain the main optical concepts involved in the structural color generation.