Description
Optical chirality is a consistent topic of interest due to its diverse applications in medical research, particularly for drug design where proteins frequently exhibit distinct enantioselectivity toward binding partners [1,2]. Meta-optical designs can significantly enhance structural chiral responses by altering intrinsic symmetry using techniques such as chiral meta-atoms and monoclinic lattices [3, 4]. Another route has been utilising 2D materials to filter chiral light using twisted moiré heterostructures to generate an intrinsic chirality [5]. One work of note used this methodology with the optically anisotropic material $\text{MoOCl}_2$ and patterned a metasurface to exhibit a chiral response [6]. However, to receive very high chiral responses, these approaches often rely on complex, high-precision patterning that complicates scalable fabrication.
Our structure expands on this design to dramatically increase chiroptical performance. We found that by utilising a bilayer thin-film system of different thicknesses, a simulated circular dichroism (CD) — defined here as the normalised optical response difference to circularly polarised light — of up to 0.985 could be achieved without any additional chiral geometry. Furthermore, our results indicate that this thickness difference is the determining factor in the chiral response. By further probing this structure, we demonstrate a simpler fabrication process achieving near-unity CD. This mechanism effectively shifts the design challenge from intricate lithography to straightforward vertical layer control, opening an avenue for easily manufactured, high-performance chiroptical devices.
References:
[1] A. Rodger and B. Nordén, Circular Dichroism and Linear Dichroism (Oxford University Press, Oxford, 1997).
[2] W. H. Brooks, W. C. Guida, and K. G. Daniel, Curr. Top. Med. Chem. 11, 760 (2011).
[3] Q.-M. Deng et al., npj Nanophotonics 1, 20 (2024).
[4] I. Toftul et al., Phys. Rev. Lett. 133, 216901 (2024).
[5] C.-J. Kim et al., Nat. Nanotechnol. 11, 520 (2016).
[6] Y. Li et al., Nat. Commun. 17, 2716 (2026).
| I am the presenting author | Yes |
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