Controlling graphene plasmons with a zero-index metasurface.

Area of Science:

• Condensed Matter Physics
• Nanophotonics
• Metamaterials

Background:

• Graphene plasmons offer diverse nanoscale applications but precise propagation control remains a challenge.
• Metasurfaces with zero refractive index are emerging as powerful tools for manipulating light-based phenomena.

Purpose of the Study:

• To propose and demonstrate an on-chip integrated platform for engineering graphene plasmon wave fronts.
• To utilize a zero-index metasurface to achieve precise control over graphene plasmon propagation.

Main Methods:

• Design and fabrication of a graphene/photonic-crystal metasurface with a zero effective refractive index.
• Theoretical analysis and simulation of plasmonic dispersion and wave front engineering.
• Experimental validation of plane-wave emission and focusing effects.

Main Results:

• The designed metasurface exhibits conical plasmonic dispersion with a triply degenerate state at the Dirac frequency, creating a zero-effective-index for graphene plasmons.
• Demonstration of plane-wave emission and focusing of graphene plasmons by tailoring the zero-index metasurface.
• Achieved tunable Dirac point frequency via electrical tuning of graphene Fermi level.

Conclusions:

• The developed on-chip platform enables active control over graphene plasmon propagation.
• The zero-effective-index metasurface provides a novel approach for manipulating nanoscale light.
• This technology holds potential for advanced integrated photonic circuits and devices.