Direct imaging of localized surface plasmon polaritons

Area of Science:

• Photonics and Nanophotonics
• Plasmonics
• Optical Metamaterials

Background:

• Localized surface plasmon polaritons (SPPs) are crucial for nanoscale light manipulation.
• Coupled plasmonic cavities offer unique waveguiding properties.
• Direct imaging of SPPs within these structures is essential for understanding their behavior.

Purpose of the Study:

• To demonstrate dark field imaging of SPPs in plasmonic coupled cavities.
• To investigate the localization and dispersion of plasmonic cavity modes.
• To validate experimental findings with theoretical calculations.

Main Methods:

• Utilized dark field imaging in the Kretschmann configuration.
• Employed a tunable supercontinuum white-light laser with an acousto-optic tunable filter.
• Performed polarization-dependent spectroscopic reflection and dark field imaging.

Main Results:

• Successfully imaged scattered light from SPPs within plasmonic cavities.
• Measured the localization and dispersion of plasmonic cavity modes by tuning the excitation wavelength.
• Experimental results showed strong agreement with finite-difference time-domain (FDTD) calculations.

Conclusions:

• Dark field imaging is an effective technique for visualizing SPPs in plasmonic waveguiding bands.
• The study provides valuable insights into the mode characteristics of coupled plasmonic cavities.
• This work facilitates the development of advanced plasmonic devices and integrated photonic circuits.