Butterfly-inspired photonics reverse diffraction color sequence.

Abstract

Biological systems have been an infinite reservoir of inspiration ever since humans started to develop tools and machinery. Just as early scientists and engineers attempted to mimic birds and fish in the development of flying machines and submarines, today, new technologies find their inspiration from biology, such as gecko feet (1), antireflective eye lenses (2), iridescent insects (3), and water-repellant surfaces (4). Incorporating biological systems and concepts into technological design can happen in several ways: inspiration, mimicking, and replication (5). In the latter, entire organisms or body parts are directly used, and their structural features are replicated into another compound (6⇓–8). Examples include 3D photonic crystals from iridescent beetle scales (9, 10) or antireflective microlens arrays from insect eyes (11, 12). In contrast, in bioinspiration and biomimicry, a biological function or activity—rather than the organism itself—is converted into an artificial, human-made material or device. In PNAS, England et al. report an optical micrograting array inspired by a photonic structure found in iridescently colored butterfly wings (13). The authors demonstrate a micrograting array that not only mimics the unique diffraction properties of the biological structure with reversed color-order sequence, but also can be designed to tune these optical properties.