Surface Plasmon Polariton Interference in Gold Nanoplates.

Area of Science:

• Plasmonics and Nanophotonics
• Optical Physics

Background:

• Surface plasmon polariton (SPP) modes are crucial for understanding light-matter interactions in metal nanostructures.
• Studying SPP modes in gold nanoplates requires advanced optical techniques to probe their wavevector properties.

Purpose of the Study:

• To investigate the optical properties of SPP modes in gold nanoplates using transient absorption microscopy (TAM).
• To determine the wavevector of the bound SPP mode through optical measurements.

Main Methods:

• Utilized transient absorption microscopy (TAM) to observe interference patterns in gold nanoplates.
• Employed back focal plane imaging to measure the wavevector of leaky SPP modes.
• Combined TAM interference data with leaky mode wavevector measurements to deduce bound mode wavevector.

Main Results:

• Observed interference oscillations in TAM images of thin gold nanoplates, attributed to bound and leaky SPP mode interference.
• Determined the interference wavelength (λ = 2π/Δk) is sensitive to the dielectric environment above the nanoplates.
• Successfully measured the bound mode wavevector using a combination of TAM and back focal plane imaging.

Conclusions:

• These experiments demonstrate the first far-field optical measurement of the bound mode wavevector in metal nanostructures.
• The findings provide new insights into the fundamental optical properties and behavior of SPP modes in plasmonic nanostructures.
• This technique offers a pathway for characterizing dielectric environments using plasmonic nanostructures.