Highly Unidirectional Radiation Enhancement Based on a Hybrid Multilayer Dimer

Area of Science:

• Plasmonics and Nanophotonics
• Metamaterials
• Quantum Optics

Background:

• Plasmonic dimers offer strong field enhancement but suffer absorption losses.
• Dielectric dimers provide low loss but have weak optical confinement.
• Hybrid nanoantennas aim to combine the benefits of both plasmonic and dielectric structures.

Purpose of the Study:

• To propose and investigate a novel hybrid nanoantenna design based on a metal-dielectric-metal (MDM) dimer.
• To explore the optical properties, specifically unidirectional forward scattering and Kerker conditions, of the proposed hybrid dimer.
• To evaluate the performance of the hybrid dimer when coupled with electric quantum emitters, focusing on radiation directivity and efficiency.

Main Methods:

• Theoretical modeling and simulation of a hybrid nanoantenna composed of core-dual shell nanoparticles (MDM structure).
• Analysis of scattering properties, including field enhancement and suppression of losses.
• Investigation of the interaction between the hybrid dimer and coupled electric quantum emitters.

Main Results:

• The hybrid dimer exhibits unidirectional forward scattering, approaching an ideal Kerker condition near resonance.
• This is achieved by enhancing and superimposing high-order electric and magnetic multipoles within the dimer gap.
• Coupling with quantum emitters shows the hybrid dimer offers significantly improved radiation directivity (53x higher back-to-front ratio) and radiation efficiency (80% higher) compared to pure dielectric or metallic dimers, respectively.
• Hybrid hexamers based on this dimer structure reduce radiation beamwidth by 75%, further enhancing directivity.

Conclusions:

• The proposed MDM hybrid dimer nanoantenna effectively overcomes the limitations of purely plasmonic or dielectric counterparts.
• It demonstrates superior control over light scattering, achieving near-ideal Kerker conditions and high directivity with low loss.
• This design holds promise for advanced nanophotonic applications requiring efficient light manipulation and enhanced light-matter interactions.