Plexcitonic Quasi-Bound States in the Continuum.

Area of Science:

• Nanophotonics and Optoelectronics
• Light-Matter Interactions
• Plasmonics and Plexcitonics

Background:

• Enhancing light-matter interactions is crucial for nanophotonics and optoelectronics.
• Dielectric platforms suffer from light diffraction, while metallic systems experience energy loss, creating a trade-off.
• Bound states in the continuum (BICs) offer a way to decouple light and minimize losses.

Purpose of the Study:

• To present a general framework for conceptualizing and demonstrating quasi-bound states in the continuum (quasi-BICs).
• To achieve quasi-BICs in lossy metallic nanostructures by minimizing energy loss and diffraction.
• To explore the extension of this framework to plexcitonic quasi-BICs.

Main Methods:

• Utilized a theoretical framework based on two-coupled resonances.
• Numerically demonstrated the creation of quasi-BICs through the interference of two bare resonance modes.
• Extended the framework to realize plexcitonic quasi-BICs on metallic systems.

Main Results:

• Achieved quasi-BICs in lossy metallic nanostructures with a considerably narrowed spectral line shape.
• Demonstrated the realization of plexcitonic quasi-BICs using the same framework.
• Showcased strong mode robustness against parameter variations due to the topological nature of the quasi-BICs.

Conclusions:

• The proposed framework offers a general method to create quasi-BICs in metallic systems, overcoming traditional limitations.
• Plasmonic and plexcitonic quasi-BICs provide a robust platform for manipulating photophysical properties.
• This work unlocks potential for advanced coupled plasmon-exciton systems in condensed phases.