Effective surface conductivity of optical hyperbolic metasurfaces: from far-field characterization to surface wave...

Area of Science:

• Nanophotonics
• Plasmonics
• Metasurface Optics

Background:

• Metasurfaces enable optical field control via engineered meta-atoms.
• Controlling near- and far-fields is crucial for nanoscale and photonic applications.
• Spatial dispersion effects are significant in metasurface near-field regimes.

Purpose of the Study:

• To demonstrate that a local surface conductivity tensor effectively describes resonant plasmonic hyperbolic metasurfaces.
• To validate this tensor's accuracy in both far-field and near-field optical regimes.
• To provide a practical method for characterizing metasurfaces using effective conductivity.

Main Methods:

• Retrieving effective surface conductivity tensor from experimental and numerical reflectance spectra.
• Analyzing metasurfaces composed of elliptical gold nanoparticles.
• Validating conductivity using nonlocal discrete dipole models with and without inter-meta-atom interactions.

Main Results:

• The effective surface conductivity tensor accurately describes metasurface optical properties across near- and far-field regimes.
• Validated conductivity parameters correctly predict quasi-TE and quasi-TM plasmon dispersion laws.
• The model accurately captures the topological transition from elliptical to hyperbolic regimes.

Conclusions:

• A local surface conductivity tensor provides a robust and simple model for resonant plasmonic hyperbolic metasurfaces.
• This approach allows accurate characterization of metasurface properties, including near-field behavior.
• Far-field characterization can be leveraged to extract effective conductivity for near-field analysis.