Bragg-mirror-like circular dichroism in bio-inspired quadruple-gyroid 4srs nanostructures

The smooth and tailorable spectral response of Bragg mirrors has driven their pervasive use in optical systems requiring customizable spectral control of beam propagation. However, the simple nature of Bragg mirror reflection prevents their application to the control of important polarization states such as circular polarization. While helical and gyroid-based nanostructures exhibiting circular dichroism have been developed extensively to address this limitation, they are often restricted by the spectral inconsistency of their optical response. Here we present the fabrication and characterization of quadruple-gyroid 4srs nanostructures exhibiting bio-inspired Bragg-mirror-like circular dichroism: a smooth and uniform band of circular dichroism reminiscent of the spectrum of a simple multilayer Bragg-mirror. Furthermore, we demonstrate that the circular dichroism produced by 4srs nanostructures are robust to changes in incident angle and beam collimation, providing a new platform to create and engineer circular dichroism for functional circular polarization manipulation. Inspired by the intricate design of butterfly wing scales, scientists have made nanostructures that exhibit strong circular dichroism. Bragg mirrors are vital building blocks of many optical systems, but they cannot be used to control important polarization states such as circular polarization. Now, Benjamin Cumming of RMIT University in Australia and co-workers have made nanostructures that transmit only a single handedness (left or right) of circular polarization while reflecting the other. They fabricated these structures by nanostructuring a thin layer of the chalcogenide glass arsenic trisulfide (As2S3) using a direct laser writing system enhanced by adaptive optics. The circular dichroism of the nanostructures is highly robust to changes in the angle or collimation of the incident light. The design is promising for fabricating chiral photonic devices.