Artificial Propeller Chirality and Counterintuitive Reversal of Circular Dichroism in Twisted Meta-molecules

Here we demonstrate an optical propeller chirality in artificially twisted meta-molecules, which is remarkably different from conventional optical helical chirality. Giant circular dichroism (CD) is realized in a single layer of meta-molecule array by utilizing the surface lattice resonances that are formed by the coupling of chiral electric quadrupole modes to the diffractive lattice mode. Due to the special twist of the propeller blades, the periodic meta-molecule array is hybridized by unit cells with two different chiral centers. As a result, the CD response is readily reversed by tailoring the interference phase through engineering the structural blades without inverting the geometric chirality. Importantly, the enhanced CD and its sign reversal are demonstrated in experiments by using a nano-kirigami fabrication technique.

Automated summary

In this study, an optical propeller chirality in artificially twisted meta-molecules is demonstrated, which is remarkably different from conventional optical helical chirality, resulting in giant circular dichroism (CD) in a single layer of meta-molecule array. The periodic meta-molecule array is hybridized by unit cells with two different chiral centers due to the special twist of the propeller blades, and the CD response can be readily reversed by tailoring the interference phase through engineering the structural blades without inverting the geometric chirality, as demonstrated in experiments using a nano-kirigami fabrication technique.