An electrically excited nanoscale light source with active angular control of the emitted light

Area of Science:

• Nanophotonics
• Plasmonics
• Scanning Probe Microscopy

Background:

• Localized surface plasmons (LSP) are collective oscillations of electrons in nanoparticles.
• Controlling light emission at the nanoscale is crucial for advanced optical technologies.
• Scanning tunneling microscopy (STM) enables precise manipulation and excitation at the nanoscale.

Purpose of the Study:

• To investigate the control of light emission from individual gold nanoparticles.
• To analyze the angular distribution, polarization, and spectrum of emitted light.
• To understand the underlying physics of electrically controlled plasmonic light sources.

Main Methods:

• Chemically synthesized gold nanoparticles (truncated bitetrahedrons) were used as nanoscale light sources.
• Localized surface plasmons (LSP) were excited using a scanning tunneling microscope (STM).
• Emission characteristics were analyzed via collected light through a transparent substrate.

Main Results:

• Emitted light properties strongly depended on the STM tip's lateral position relative to the nanoparticle.
• Light emission orientation changed when the STM tip moved from the base to the vertex of the nanoparticle.
• Selective excitation of in-plane and out-of-plane dipolar LSP modes was achieved by controlling tip position.

Conclusions:

• The study demonstrates precise electrical control over nanoscale light emission.
• Lateral positioning of the STM tip allows selective excitation of specific plasmon modes.
• This work provides a pathway for designing tunable nanoscale light sources.