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Fourier Plane Tomographic Spectroscopy Reveals Orientation-Dependent Multipolar Plasmon Modes in Micrometer-Scale
Felix H Patzschke1, Frank Cichos1
1Molecular Nanophotonics Group, Peter Debye Institute for Soft Matter Physics, Leipzig University, 04103 Leipzig, Germany.
ACS Nano
|March 23, 2026
Summary
We developed a new spectroscopy method to study light scattering from plasmonic Janus particles (pJPs). This technique reveals orientation-dependent optical properties, enabling precise tracking of particle rotation.
Area of Science:
- Plasmonics and Nanophotonics
- Light-Matter Interactions
- Materials Science
Background:
- Precise control of light-matter interactions is crucial for advanced technologies like biosensing and metamaterials.
- Micrometer-scale plasmonic Janus particles (pJPs) have complex optical properties due to their asymmetry, but their orientation-dependent scattering is poorly understood.
Purpose of the Study:
- To develop a method for characterizing the orientation-dependent scattering properties of individual micrometer-scale pJPs.
- To identify spectral markers and understand the multipolar modes governing light scattering from pJPs.
Main Methods:
- Fourier plane tomographic spectroscopy for simultaneous 4D characterization (wavelength, incident angle, scattering angle, time).
- Finite-element simulations to complement experimental measurements.
- Spherical-harmonics decomposition to analyze scattering patterns and identify multipolar modes.
Main Results:
- Identified discrete spectral markers in the visible and near-infrared regions that correlate with pJP cap orientation.
- Revealed three distinct multipolar modes (axial-propagating transverse-electric, transverse-propagating transverse-electric, transverse-propagating axial-electric) up to fifth order.
- Observed curvature-dependent mode dispersion (red-shifts, line width narrowing) and polarization-dependent scattering patterns for optical tracking.
Conclusions:
- The developed methodology enables precise characterization of asymmetric nanostructures.
- The findings provide a toolkit for designing orientation-responsive nanoantennas, reconfigurable metasurfaces, and active colloidal systems.
- This work facilitates high-precision optical tracking of particle rotation and tailored light-matter interactions.
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