Chiral photonic super-crystals based on helical van der Waals homostructures

TL;DR

This paper demonstrates the creation of chiral photonic super-crystals using helical van der Waals homostructures, enabling new ways to control light-matter interactions based on tailored layered materials.

Contribution

It introduces a novel method to engineer chiral optical properties in layered van der Waals structures without patterning, using helical arrangements of multilayer crystals.

Findings

Helical van der Waals structures exhibit strong chiral optical effects.

Multilayer As$_2$S$_3$ demonstrates pronounced circular dichroism.

Chirality emerges from layer arrangement, not molecular structure.

Abstract

Chirality is probably the most mysterious among all symmetry transformations. Very readily broken in biological systems, it is practically absent in naturally occurring inorganic materials and is very challenging to create artificially. Chiral optical wavefronts are often used for the identification, control and discrimination of left- and right-handed biological and other molecules. Thus, it is crucially important to create materials capable of chiral interaction with light, which would allow one to assign arbitrary chiral properties to a light field. In this paper, we utilized van der Waals technology to assemble helical homostructures with chiral properties (e. g. circular dichroism). Because of the large range of van der Waals materials available such helical homostructures can be assigned with very flexible optical properties. We demonstrate our approach by creating helical homostructures based on multilayer As$_2$S$_3$, which offers the most pronounced chiral properties even in thin structures due to its strong biaxial optically anisotropy. Our work showcases that the chirality of an electromagnetic system may emerge at an intermediate level between the molecular and the mesoscopic one due to the tailored arrangement of non-chiral layers of van der Waals crystals and without additional patterning.