A tunable plasmon resonance in gold nanobelts

Area of Science:

• Nanophotonics
• Plasmonics
• Materials Science

Background:

• Plasmonic nanostructures are crucial for manipulating light at the nanoscale.
• Understanding the optical properties of low-dimensional plasmonic systems is essential for developing new photonic devices.

Purpose of the Study:

• To investigate the plasmonic properties of sub-100-nm rectangular cross-section plasmonic nanowires.
• To correlate the optical response with the geometrical dimensions of the nanowires.

Main Methods:

• Fabrication and characterization of individual plasmonic nanobelts.
• Atomic force microscopy (AFM) for precise dimensional measurements.
• Dark-field scattering spectroscopy for optical analysis.
• Finite-difference time-domain (FDTD) simulations for mode analysis.

Main Results:

• Plasmonic nanowires with sub-100-nm rectangular cross sections exhibit a strong transverse plasmon peak in the visible spectrum.
• The transverse plasmon peak wavelength is tunable and directly correlates with the cross-sectional aspect ratio of the nanobelts.
• Simulations identify the observed plasmonic modes as transverse antisymmetric excitations across the nanobelt width.
• These nanobelts display sharp, tunable plasmon resonances, comparable to nanoparticle behavior, unlike larger diameter silver nanowires.

Conclusions:

• Sub-100-nm rectangular plasmonic nanowires offer tunable plasmon resonances dependent on their aspect ratio.
• These findings provide a pathway for designing tailored plasmonic nanostructures for specific optical applications.
• The observed tunable resonances in nanobelts present an alternative to nanoparticle-based plasmonics.