Optimal polarization conversion in coupled dimer plasmonic nanoantennas for metasurfaces

Area of Science:

• Metasurfaces
• Nanophotonics
• Antenna Design

Background:

• Coupled dimer antennas are key components in phase discontinuity metasurfaces.
• Polarization conversion is crucial for advanced optical functionalities.

Purpose of the Study:

• To demonstrate tunable polarization conversion in coupled dimer antennas.
• To explore the relationship between antenna coupling and polarization conversion.
• To develop strategies for metasurface design and polarization optics.

Main Methods:

• Fabrication and characterization of coupled dimer antennas with varying gap widths.
• Theoretical modeling using a two-oscillator approach.
• Single antenna spectroscopy to analyze mode splitting and polarization conversion.

Main Results:

• Polarization conversion is strongly dependent on the gap width, transitioning from capacitive to conductive coupling.
• A theoretical model shows universal scaling of polarization conversion with mode energy splitting.
• Demonstrated linear to circular polarization conversion in single antennas.

Conclusions:

• Precise control over antenna design enables tunable polarization conversion.
• The findings provide a pathway for developing efficient phase discontinuity metasurfaces.
• Results contribute to the advancement of ultracompact polarization optical devices.