Strong coherent coupling between graphene surface plasmons and anisotropic black phosphorus localized surface...

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanophotonics

Background:

• Black phosphorus exhibits anisotropic plasmon properties, enabling direction-dependent devices.
• Graphene surface plasmons (GSP) and black phosphorus localized surface plasmons (BPLSP) are key components in plasmonics.
• Strong coupling regimes are crucial for advanced plasmonic device functionalities.

Purpose of the Study:

• To theoretically investigate the hybridization between GSP and BPLSP in the strong coupling regime.
• To understand the role of graphene's Fermi level and black phosphorus's anisotropy in achieving coherent coupling.
• To explore the potential for creating compact anisotropic plasmonics devices using 2D materials.

Main Methods:

• Theoretical investigation of GSP-BPLSP hybridization.
• Dynamic adjustment of graphene's Fermi level to achieve strong coupling.
• Application of a coupled oscillator model to quantitatively describe hybrid mode dispersion.
• Analysis of mode splitting energy and coupling strength dependence on inter-layer distance.

Main Results:

• Achieved strong coherent GSP-BPLSP coupling in both armchair and zigzag directions by tuning graphene's Fermi level.
• Attributed coupling to black phosphorus's anisotropic effective electron masses.
• Quantified mode splitting energies of 26.5 meV (armchair) and 19 meV (zigzag).
• Demonstrated that coupling strength is sensitive to the separation distance between graphene and black phosphorus.

Conclusions:

• The study successfully demonstrates strong plasmon hybridization between graphene and anisotropic black phosphorus.
• This hybridization is tunable via graphene's Fermi level and influenced by black phosphorus's intrinsic anisotropy.
• The findings provide a foundation for developing novel, compact anisotropic plasmonics devices for infrared and terahertz applications.