Extreme Optical Properties Tuned Through Phase Substitution in a Structurally Optimized Biological Photonic Polycrystal

Authors

  • Xia Wu,

    1. Max-Planck-Institut für Eisenforschung GmbH, Department of Microstructure Physics and Alloy Design, Max-Planck-Str. 1, 40237 Düsseldorf, Germany
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  • Andreas Erbe,

    1. Max-Planck-Institut für Eisenforschung GmbH, Department of Interface Chemistry and Surface Engineering, Max-Planck-Str. 1, 40237 Düsseldorf, Germany
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  • Dierk Raabe,

    1. Max-Planck-Institut für Eisenforschung GmbH, Department of Microstructure Physics and Alloy Design, Max-Planck-Str. 1, 40237 Düsseldorf, Germany
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  • Helge-Otto Fabritius

    Corresponding author
    1. Max-Planck-Institut für Eisenforschung GmbH, Department of Microstructure Physics and Alloy Design, Max-Planck-Str. 1, 40237 Düsseldorf, Germany
    • Max-Planck-Institut für Eisenforschung GmbH, Department of Microstructure Physics and Alloy Design, Max-Planck-Str. 1, 40237 Düsseldorf, Germany.
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Abstract

Biological photonic structures evolved by insects provide inspiring examples for the design and fabrication of synthetic photonic crystals. The small scales covering the beetle Entimus imperialis are subdivided into irregularly shaped domains that mostly show striking colors, yet some appear colorless. The colors originate from photonic crystals consisting of cuticular material and air, which are geometrically separated by a triply periodic D-surface (diamond). The structure and orientation of the photonic crystals are charactized and it is shown that in colorless domains SiO2 substitutes the air. The experimental results are incorporated into a precise D-surface structure model used to simulate the photonic band structure. The study shows that the structural parameters in colored domains are optimized for maximum reflectivity by maximizing the stop gap width. The colorless domains provide a biological example of how the optical appearance changes through alteration of the refractive index contrast between the constituting phases.

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