Employing quasidegenerate optical modes for chiral sensing

Almousa, S. F., Weiss, T. ORCID: https://orcid.org/0000-0001-8065-4108 and Muljarov, E. A. ORCID: https://orcid.org/0000-0002-2878-4148 2024. Employing quasidegenerate optical modes for chiral sensing. Physical Review B (condensed matter and materials physics) 109 (4) , L041410. 10.1103/PhysRevB.109.L041410

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Abstract

Chiral molecules cannot be superposed with their own mirror image. This yields two enantiomers of opposite handedness that are made out of the same building blocks, but interact differently with their environment. Hence, chiral sensing is of utmost importance for biology, chemistry, and life sciences. However, the impact of the handedness and chirality is very weak in most sensing schemes. Nevertheless, it has been demonstrated recently that chirality may result in strong coupling between resonant states with high quality factors. This is achieved by spectrally overlapping two quasibound states in the continuum in a periodic array of nanostructures. We demonstrate that this requires neither quasibound states in the continuum nor periodic arrays, which is exemplified for three achiral systems: a sphere with equal permittivity and permeability, a single core-shell structure, and a dielectric metasurface. For such achiral systems, we have shown previously that isolated resonant states exhibit a quadratic energy shift in the Pasteur parameter. However, for quasidegenerate states, we observe, using the rigorous resonant-state expansion and full-wave simulations, a linear energy shift and linear splitting in the presence of a chiral medium or molecule. Thus, the splitting is more sensitive to low concentrations of chiral molecules, which paves the way for novel chiral sensing schemes.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Publisher:	American Physical Society
ISSN:	2469-9950
Date of First Compliant Deposit:	29 January 2024
Date of Acceptance:	2 January 2024
Last Modified:	31 Jan 2024 16:30
URI:	https://orca.cardiff.ac.uk/id/eprint/165889

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