Lattice Resonances Excited by Finite-Width Light Beams

Area of Science:

• Plasmonics and Nanophotonics
• Optical properties of metamaterials
• Collective phenomena in nanostructures

Background:

• Periodic arrays of metallic nanostructures support lattice resonances, offering stronger and narrower optical responses than individual localized plasmons.
• Most theoretical studies analyze lattice resonances under simplified plane-wave excitation, which deviates from realistic experimental conditions using finite-width beams.

Purpose of the Study:

• To comprehensively investigate the optical response of metallic nanostructure arrays excited by finite-width light beams under paraxial and nonparaxial conditions.
• To explore behaviors unique to finite-width beam excitation that are missed in plane-wave analyses.
• To determine optimal beam widths for maximizing optical responses and understand the interplay of finite-size effects.

Main Methods:

• Theoretical analysis of periodic metallic nanostructure arrays.
• Simulation of optical responses under finite-width light beam excitation (paraxial and nonparaxial).
• Investigation of the influence of beam width on collective resonance behavior and spatial extent.

Main Results:

• The optical response becomes more collective and approaches the plane-wave limit as the excitation beam width increases.
• Optimal finite beam widths were identified for achieving the strongest lattice resonance optical responses.
• The combination of finite array size and finite beam width significantly impacts the system's optical response.

Conclusions:

• Finite-width beam excitation reveals novel optical behaviors in periodic nanostructures not observed under plane-wave conditions.
• Understanding these behaviors is crucial for designing and optimizing plasmonic devices and nanophotonic systems.
• This work provides a theoretical foundation for experiments utilizing finite-width light sources to probe lattice resonances.