Maximal optical chirality via mode coupling in bilayer metasurfaces

TL;DR

This paper demonstrates how bilayer metasurfaces with engineered mode coupling can achieve maximal optical chirality, expanding the design possibilities for chiral photonic devices and applications.

Contribution

It introduces a novel approach using bilayer membrane metasurfaces with mode coupling and engineered dissipation to maximize optical chirality.

Findings

Strong coupling of photonic eigenmodes enhances chirality.

Engineered dissipation losses enable new chirality maximization scenarios.

The approach broadens the design space for chiral nanophotonic devices.

Abstract

Recent advances in the physics of resonant optical metasurfaces allowed to realize the so-called maximum chirality of planar structures by engineering their geometric parameters. Here we employ bilayer membrane metasurfaces with a square lattice of rotated C$_4$-symmetric holes and uncover very different scenarios of chirality maximization by virtue of strong coupling of photonic eigenmodes of the membranes supplemented by smart engineering of dissipation losses. Our findings substantially expand the class of planar maximally chiral resonant surfaces feasible for widespread nanolithography techniques desired for metaphotonic applications in chiral sensing, chiral light emission, detection and polarization conversion.