Structural colors with angle-insensitive optical properties generated by Morpho-inspired 2PP structures

Gordon Zyla,Stanislav Gorb,Alexander Kovalev,Yongfeng Lu,Cemal Esen,Evgeny L Gurevich,Ying Liu,Andreas Ostendorf

doi:10.1007/s00339-020-03931-6

Gordon Zyla, Stanislav Gorb + Show 6 more

Open Access

https://doi.org/10.1007/s00339-020-03931-6

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Abstract

This paper describes how two-photon polymerization was used to generate biomimetic nanostructures with angle-insensitive coloration inspired by the blue butterflies of Morpho. Less angle dependence was achieved by engineering the structures with a certain degree of disorder, which delimited them from classical photonic crystals. Variations in the processing parameters enabled the color hue to be controlled. In this context, blue, green, yellow, and brown structures were demonstrated. Reflection spectra of the structures were simulated and studied experimentally in a broad range of incident angles. Additionally, a molding technique was performed as a potential scale-up strategy. The application of such biomimetic structures is discussed.

Highlights

Structural colors in nature result from interference, diffraction, or scattering of light
Page 3 of 11 740 the color appears to be angle-insensitive to an observer in an angle range of ± 15° [15], which in turn, does not match the optical properties of a conventional multilayer system
Inhomogeneity can be identified inside the multilayer systems, which significantly influences the angle-insensitivity of the observed coloration [16, 34, 35]

Summary

Introduction

Structural colors in nature result from interference, diffraction, or scattering of light. The photonic systems of many species often exhibit disorder characteristics [5, 9], which can be attributed to single structural impurities or a complex spatial distribution of the structures and their periodicity on the organisms’ surfaces In this context, the disorder characteristics can cause extraordinary optical effects, e.g., the ultrawhite color of the Cyphochilus [10], the ultrablack color of the Bitis gabonica [11, 12], and the iridescent green color of the Chrysina gloriosa [13], because one but multiple physical mechanisms participate in the color formation. Their intense coloration is primarily to appear highly attractive since its color appears less angle dependent to an observer than in conventional optical diffraction gratings [5, 14,15,16,17,18]

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