Nonlinear Strong Coupling by Second-Harmonic Generation Enhancement in Plasmonic Nanopatch Antennas

Area of Science:

• Plasmonics and Nanophotonics
• Nonlinear Optics
• Quantum Optics

Background:

• Plasmonic nanocavities enhance electromagnetic fields, enabling applications in linear and nonlinear optics.
• Second harmonic generation (SHG) is a key nonlinear optical process with applications in frequency conversion.
• Controlling light-matter interactions is crucial for advanced optical devices.

Purpose of the Study:

• To demonstrate enhanced second harmonic generation from individual plasmonic nanopatch antennas.
• To investigate the integration of quantum emitters for strong coupling effects.
• To explore the potential of nanopatch antennas for nonlinear control of light-matter interactions.

Main Methods:

• Fabrication of plasmonic nanopatch antennas using silver nanocubes and a zinc oxide spacer layer on a gold film.
• Excitation of antennas at their fundamental plasmon frequency to observe SHG.
• Integration of quantum emitters and measurement of exciton-polariton strong coupling.

Main Results:

• Observed a 10^4-fold increase in the intensity of the second harmonic generation wave.
• Demonstrated a second-order nonlinear exciton-polariton strong coupling response with a Rabi splitting energy of 19 meV.
• Validated the platform for nonlinear control of light-matter interactions in both weak and strong coupling regimes.

Conclusions:

• Plasmonic nanopatch antennas significantly enhance nonlinear optical processes like SHG.
• The platform facilitates strong coupling between quantum emitters and plasmonic modes.
• This research provides a versatile platform for optical engineering and information processing applications.