Gyroid optical metamaterials consist of triply periodic chiral networks that are attractive photonic structures due to the combination of intriguing optical properties and spontaneous self‐assembly‐based fabrication routes using materials such as block copolymers. A previous experimental investigation found that gyroid metamaterials support strong circular dichroism, beyond what simulations only considering bulk interactions predict. In this work, simulations are used to unravel the contributions of bulk and surface interactions on the circular dichroism spectra of silver‐infilled gyroid metamaterial films. It is found that surface interactions have a significant, often dominating, contribution to circular dichroism. The relative strength of bulk and surface contributions can be tuned by controlling the crystallographic orientation, termination plane of the film, thickness, metal volume fraction, and defect density. Importantly, the dominance of surface interactions allows double gyroids, which are achiral in the bulk, to support strong circular dichroism responses with
The integration of chiral organization with photonic structures found in many living creatures enables unique chiral photonic structures with a combination of selective light reflection, light propagation, and circular dichroism. Inspired by these natural integrated nanostructures, hierarchical chiroptical systems that combine imprinted surface optical structures with the natural chiral organization of cellulose nanocrystals are fabricated. Different periodic photonic surface structures with rich diffraction phenomena, including various optical gratings and microlenses, are replicated into nanocellulose film surfaces over large areas. The resulting films with embedded optical elements exhibit vivid, controllable structural coloration combined with highly asymmetric broadband circular dichroism and a microfocusing capability not typically found in traditional photonic bioderived materials without compromising their mechanical strength. The strategy of imprinting surface optical structures onto chiral biomaterials facilitates a range of prospective photonic applications, including stereoscopic displays, polarization encoding, chiral polarizers, and colorimetric chiral biosensing.
more » « less- Award ID(s):
- 1803495
- NSF-PAR ID:
- 10448295
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials
- Volume:
- 32
- Issue:
- 2
- ISSN:
- 0935-9648
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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