All things bright and beautiful: light and colour manipulation in biology

The study of structural colour in biological systems is an exciting interdisciplinary research area. Photonic bandgap (PBG) structures in many animals and plants suggest broad innovation in nature’s use of materials to manipulate light. In certain butterflies long-range visibility of up to one kilometre is attributed to nano- and micro-structures formed by discrete multilayers of cuticle and air. This contrasts to other butterfly photonic structures designed for camouflage that not only produce strong polarisation effects but also create additive colour mixing using highly adapted geometries. Optical systems also exist that employ remarkable 2D and 3D photonic crystals to produce partial PBGs, with the effect that bright colour is reflected, or fluorescence emission is inhibited, over specific angle ranges. From the perspective of optical technology, these structures indicate a significant evolutionary step since they are potentially able to manipulate the flow of light in all directions. This lecture will present an overview of this field of study, as well as several of the exciting recent discoveries that reflect nature’s optical design ingenuity.