Direct Visualization of Counter-Propagating Surface Plasmons in Real Space-Time

Area of Science:

• Plasmonics
• Nanophotonics
• Surface Science

Background:

• Surface plasmon polaritons (SPPs) are crucial for nanoscale light manipulation.
• Characterizing SPP dynamics is essential for developing advanced photonic devices.
• Existing methods often face challenges with excitation field interference.

Purpose of the Study:

• To develop a novel method for interference-free imaging of SPP wave packets.
• To enable direct spatiotemporal characterization of SPPs.
• To investigate the benefits of counter-propagating SPPs.

Main Methods:

• Utilizing two-dimensional nanohole arrays as resonant SPP couplers.
• Employing two-color photoemission electron microscopy for spatiotemporal monitoring.
• Recording SPP trajectories for co- and counter-propagating directions.

Main Results:

• Achieved interference-free imaging of SPP wave packets.
• Successfully tracked the real-space and real-time evolution of SPP electric field envelopes.
• Demonstrated direct characterization of SPP spatiotemporal properties.
• Analyzed SPP trajectories for both propagation directions.

Conclusions:

• Nanohole arrays effectively enable counter-propagation of SPPs.
• Counter-propagation suppresses excitation field-SPP interactions, enhancing clarity.
• The developed technique offers significant advantages for studying SPP dynamics.