# Mapping Optical Chirality with Single Fluorescent Molecules

## TL;DR

Researchers used single fluorescent molecules to map the structure of chiral light fields at the nanoscale, revealing how light interacts with matter.

## Contribution

This work introduces single fluorescent molecules as quantitative nanoprobes for mapping optical chirality and polarization.

## Key findings

- Single molecules can visualize the handedness of circularly polarized light at the nanoscale.
- Measured fluorescence patterns align with vectorial diffraction models, revealing molecular orientations and field structures.
- The method enables accurate characterization of complex light fields in nanophotonic and plasmonic systems.

## Abstract

Single fluorescent molecules, acting as ideal point dipoles,
offer
a unique means to probe light–matter interactions
at the nanoscale. Here, we exploit this property to
map the chiral and vectorial structure of tightly focused optical
fields using individual, immobilized terrylene diimide molecules.
By scanning the excitation focus under linear and circular polarization,
we obtain three-dimensional fluorescence excitation maps that directly
visualize the handedness and symmetry breaking inherent to circularly
polarized light. The measured patterns show excellent quantitative
agreement with a full vectorial diffraction model, enabling the accurate
determination of both molecular orientations and the local field structure.
This approach establishes single molecules as quantitative nanoprobes
of optical chirality, offering new strategies for characterizing complex
light fields and polarization effects in nanophotonic, plasmonic,
and anisotropic materials.