Subwavelength Plasmonic Antennas Based on Asymmetric Split-Ring Resonators for High Near-Field Enhancements

Area of Science:

• Plasmonics
• Nanophotonics
• Metamaterials

Background:

• Plasmonic antennas commonly utilize electric dipole resonance, which presents limitations for optimization.
• Achieving strong near-field enhancement is crucial for applications in spectroscopy and light-matter interactions.

Purpose of the Study:

• To propose and demonstrate a novel plasmonic antenna design, the asymmetric split-ring resonator (ASRR), for enhanced near-field generation.
• To overcome the limitations of conventional electric dipole resonance-based antennas.

Main Methods:

• Development of the ASRR design through a hybrid framework combining evolutionary optimization and residual neural networks.
• Simplification of the optimized configuration into a practical ASRR prototype.
• Experimental and simulation-based characterization of the ASRR dimer's performance.

Main Results:

• The ASRR induces differential charge distribution, localizing charges for efficient near-field enhancement.
• ASRR dimers exhibit over a 6-fold increase in electric-field intensity enhancement compared to nanorod dimers at the subwavelength scale.
• Demonstrated superior Purcell factor and fluorescence enhancement using the ASRR.

Conclusions:

• The ASRR design offers a significant advancement in plasmonic antenna performance.
• This breakthrough provides new opportunities for surface-enhanced spectroscopy and tailored light-matter interactions.
• The ASRR represents a promising platform for next-generation nanophotonic devices.