Quasi-ordered plasmonic metasurfaces with unclonable stochastic scattering for secure authentication.

Area of Science:

• Nanotechnology and Photonics
• Materials Science
• Applied Physics

Background:

• Nature exhibits structural coloration with quasi-order, providing unique near-field fingerprints and uniform far-field colors.
• Replicating this dual characteristic in artificial photonic metasurfaces is a significant scientific challenge.

Purpose of the Study:

• To engineer plasmonic metasurfaces that balance quasi-ordered structural coloration with unique near-field stochastic properties.
• To develop physically unclonable functions (PUFs) for secure authentication and anti-counterfeiting applications.

Main Methods:

• Electrostatic self-assembly of gold nanoparticles onto a dielectric-spaced metallic mirror.
• Fabrication of plasmonic metasurfaces with tunable dielectric gap thickness.
• Characterization of far-field reflective colors and near-field scattering patterns.

Main Results:

• Achieved tunable far-field colors across the visible spectrum by adjusting dielectric gap thickness.
• Generated stochastic near-field scattering patterns functioning as unique, unclonable physically unclonable functions (PUFs).
• PUF keys demonstrated high uniformity (0.501), uniqueness (0.496), large capacity (~10^260), and environmental stability.

Conclusions:

• Plasmonic metasurfaces successfully replicate nature's balance of uniform far-field color and unique near-field fingerprints.
• The developed PUFs offer robust security features resistant to cloning and environmental degradation.
• Demonstrated practical applications in information camouflage and secure identification elements.