Preparation Of Photonic Crystals Based On Biological Structure And Its Optical Properties

In nature, some organisms have the ability to form intricate micro-and nano-structure by evolution. In this thesis, we first study the structure and optical property of beetle Carabus lafossei. Then, based on the beetle’s structure and bicolor, we obtain bionic sample with similar structure and bicolor by optical lithography and thin film deposition. Finally, the beetle’s surface structure is used to control micro-wrinkles. The main works of this thesis are as follows:1. The surface images of beetle’s elytra are obtained by optical microscope and scanning electron microscope. Then, the cuticular structures of the ultrathin section are observed by transmission electron microscope. As the beetle displays different colors at different angles, its spectrum is measured under variable angles by a spectrometer. Finally, the measured results are confirmed by T-matrix simulations.2. The structure and bicolor of beetle’s elytra are mimiced by microfabrication. First, the sculpted hexagonal array is achieved by optical lithography. Then, the multilayer structure is achieved by evaporating alternative films on the sculpted hexagons. Finally, by changing the substrate’s reflectance of different areas, we find the same multilayer stack could also display different colors. Moreover, the range of bicolor can be tuned by controlling the substrate’s reflectance.3. The surface morphology of elytra is replicated by soft lithograph. By coating different dielectric layers on Polydimethylsiloxane (PDMS), we find wrinkling or cracking on the surface of PDMS. By using the sculpted hexagon of elytra, the micro-wrinkle can be adjusted to be aligned and periodic.