Elytra of beetles or scales of butterflies are materials that, from natural selection, evolved amazing properties (rigidity, hydrophobicity, etc.). In addition, they manipulate the light to target a specific color. The most common is the pigmentary coloration, relative to the electronic structure of the material, but the structural coloration, relative to the geometry of the material, cannot be neglected. Among the pigments stand the fluorescent molecules, able to absorb an incident flux and to emit a lower energy flux. The fluorescent sources confinement in a photonic structure modifies the phenomenon properties (incident flux absorption, emission spatial distribution, etc.). Industry, that tends to manufacture products with well-targeted features, uses a large variety of materials. The limitation comes from a lack of imagination for designing the structures in order to obtain a specific effect and from an inefficiency to generate them with the nowadays available technology. Conversely, nature offers a wide range of architectures, built from a narrow range of materials. Bio-inspiration combines both fields in order to synthesize new products. This project focused on the precise context of fluorescence confined in a natural photonic structure. Before artificially transpose the observations of nature, it was crucial to understand the underlying physics. Experimentally, the integumentary structures of some insects have been described using microscopy techniques. Reflection and emission properties were studied using angular and spectrophotometric measurements. Numerical simulations based on the scattering matrix method were conducted in order to explain the observations.
|Date of Award||14 May 2012|
|Supervisor||Jean-Pol VIGNERON (Supervisor), Philippe Lambin (Jury), Olivier DEPARIS (Jury), Christine Andraud (Jury), Serge Berthier (Supervisor), Rémi Carminati (Jury), Pierre Defrance (Jury) & Ross Mc PHEDRAN (Jury)|