The dark side of plasmonics.

Area of Science:

• Plasmonics
• Nanophotonics
• Optical Spectroscopy

Background:

• Plasmonic dark modes are collective excitations in nanoparticles with long lifetimes.
• They arise from plasmon hybridization and possess strong near-field confinement.
• Dark modes lack a net dipole moment, distinguishing them from bright modes.

Purpose of the Study:

• To demonstrate the excitation and optical detection of a collective dark plasmonic mode.
• To investigate plasmon hybridization in individual plasmonic trimers.
• To explore the potential of dark modes for applications in nanophotonics.

Main Methods:

• Fabrication of plasmonic trimers using gold nanorods in triangular arrangements.
• Optical excitation using radially polarized light.
• Experimental detection and characterization of plasmonic modes.
• Analysis using electrostatic approximation and plasmon hybridization theory.

Main Results:

• Successful excitation and optical detection of a collective dark plasmonic mode in individual trimers.
• Experimental confirmation of the lowest-energy dark mode's interaction with radially polarized light.
• Validation of dark mode assignment through plasmon hybridization theory.

Conclusions:

• Collective dark plasmonic modes can be excited and detected in individual plasmonic trimers.
• The symmetry of trimers enables interaction with specific light polarizations.
• The strong energy confinement of these dark modes is promising for strong coupling with single photon emitters.