Towards inverse design of biomimetic nanostructures exhibiting composite structural coloration

Structural color phenomena exhibited by several organisms result from interference and diffraction of light incident upon multilayer nanostructures. These biomimetic nanostructured surfaces produce structural coloration for desired angle-variant distributions of reflectance spectra. Previous work has demonstrated the utility of inverse design methodologies in the computational formulation of nanostructures tailored for specific spectral responses, generally tailored around a single spectral band. In this work, we depict a design methodology based around computational inverse design for the formulation of nanostructures exhibiting composite structural coloration in a variety of disjoint spectral bands. We furthermore depict example design constraints and study convergence with respect to the design trade space. Such complex biological systems require advanced fabrication techniques, and replication of nanoscale features of this complexity has been difficult. Our designs are constrained for realizable fabrication using direct laser writing techniques such as two-photon polymerization. This process provides a toolkit with which to examine and build other bio-inspired, tunable, and responsive photonic systems and expand the range of achievable structural colors. Sample experimental results of nanostructures fabricated via two-photon polymerization are presented.