Nanophotonic chiral sensing: How does it actually work?

Abstract

Nanophotonic chiral sensing has recently attracted a lot of attention. The idea is to exploit the strong light-matter interaction in nanophotonic resonators to determine the concentration of chiral molecules at ultra-low thresholds, which is highly attractive for numerous applications in life science and chemistry. However, a thorough understanding of the underlying interactions is still missing. The theoretical description relies on either simple approximations or on purely numerical approaches. We close this gap and present a general theory of chiral light-matter interactions in arbitrary resonators. Our theory describes the chiral interaction as a perturbation of the resonator modes, also known as resonant states or quasi-normal modes. We observe two dominant contributions: A chirality-induced resonance shift and changes in the modes excitation and emission efficiencies. Our theory brings new and deep insights for tailoring and enhancing chiral light-matter interactions. Furthermore, it allows to predict spectra much more efficiently in comparison to conventional approaches. This is particularly true as chiral interactions are inherently weak and therefore perturbation theory fits extremely well for this problem.

Main text and Supporting Information

References in corpus (6)

• Chiral plasmonics
• Brillouin-Wigner perturbation theory in open electromagnetic systems
• Resonant state expansion applied to three-dimensional open optical systems
• Simple analytical expression for the peak-frequency shifts of plasmonic resonances for sensing
• Surface Enhanced Circular Dichroism of Oriented Chiral Molecules by Plasmonic Nanostructures
• On enhanced sensing of chiral molecules in optical cavities

Cited by in corpus (5)

• Molecular-Induced Chirality Transfer to Plasmonic Lattice Modes
• Strain and Crystallographic Identification of the Helically Concaved Surfaces of Nanoparticles
• When does nonlinear circular dichroism appear in achiral dielectric nanoparticles?
• Inverse Design in the Complex Plane: Manipulating Quasi-Normal Modes
• Magnetoelectric-field electrodynamics: Search for magnetoelectric point scatterers