High-Q Nonlocal Resonances in Mirror-Enhanced Plasmonic Lattices

Area of Science:

• Nanophotonics
• Plasmonics
• Optical Metamaterials

Background:

• Plasmonic nanoparticle arrays enhance light-matter interactions.
• High-quality-factor (high-Q) resonances are crucial for selective applications.
• Achieving high-Q resonances in plasmonic systems is challenging.

Purpose of the Study:

• To develop a robust strategy for achieving high-Q resonances in plasmonic nanoparticle lattices.
• To convert bright surface lattice resonances (SLRs) into dark bound states in the continuum (BICs) using mirror-induced destructive interference.
• To realize high-Q composite plasmonic microcavities with tailored near-field properties.

Main Methods:

• Utilizing mirror-induced destructive interference to couple plasmonic nanoparticle arrays.
• Converting bright SLRs into dark BICs.
• Spatially tailoring nanoparticle orientation in composite microcavities.

Main Results:

• Demonstrated a Q factor of 3039 at ~880 nm in mirror-coupled silver nanoparticle arrays.
• Observed lasing with a minimized threshold at critical coupling.
• Realized high-Q composite plasmonic microcavities with decoupled control over Q factor and near-field topology.
• Supported vectorial lasing modes with programmable topological charges.

Conclusions:

• The developed strategy effectively achieves high-Q resonances in plasmonic nanoparticle lattices.
• Mirror-induced interference is a viable method to create dark BICs from bright SLRs.
• Tailored plasmonic microcavities enable advanced control over optical properties and lasing modes.