Security-enhanced optical image authentication based on cascaded geometric-phase metasurfaces

Area of Science:

• Optics and Photonics
• Information Security
• Materials Science

Background:

• Metasurface-based optical image authentication methods often lack physical security keys.
• Existing techniques face challenges in providing robust and physically secured authentication.

Purpose of the Study:

• To propose a security-enhanced optical image authentication method using cascaded geometric-phase metasurfaces.
• To introduce a novel approach for user identity authentication that incorporates physical security keys.

Main Methods:

• Encoding a plaintext image into an authentication amplitude via sparse constraint encoding.
• Calculating the Fourier phase-only hologram and decomposing it into ciphertext and key phases.
• Constructing physically separated ciphertext and key metasurfaces using geometric-phase metasurface units.

Main Results:

• The proposed method successfully authenticates user identity through the cascading of ciphertext and key metasurfaces.
• Numerical simulations demonstrate high feasibility and a strong security-enhanced effect.
• The method offers a large key space, enhancing overall security.

Conclusions:

• The developed cascaded geometric-phase metasurface method provides a physically secure key for optical image authentication.
• This approach overcomes limitations of current metasurface authentication systems.
• The technique shows significant promise for advanced security applications.