Multispectral metasurface hologram at millimeter wavelengths

Area of Science:

• Optics and Photonics
• Metamaterials
• Holography

Background:

• Metasurfaces offer novel ways to manipulate electromagnetic waves.
• Computer-generated holograms are crucial for advanced optical systems.
• Multi-frequency operation in holography presents unique challenges.

Purpose of the Study:

• To demonstrate a metasurface hologram encoding multiple images at distinct W-band frequencies.
• To explore the use of resonant metamaterial elements for frequency-selective image display.
• To optimize the hologram design for efficient image reconstruction.

Main Methods:

• Fabrication of a planar metasurface hologram with resonant metamaterial elements.
• Excitation of the metasurface with a collimated reference beam at an oblique angle.
• Application of the Gerschberg-Saxton algorithm for phase-only hologram optimization.
• Encoding of four distinct images using frequency-specific element subsets.

Main Results:

• Successful generation of four well-defined images at different W-band frequencies (75-110 GHz).
• Demonstration of frequency-selective image encoding by resonant metamaterial elements.
• Image reconstruction achieved within the Fresnel zone of the hologram aperture.

Conclusions:

• Computer-generated metasurface holograms can encode and reconstruct multiple images at different frequencies.
• Metasurface holography provides a versatile platform for frequency-multiplexed optical information display.
• This technology has potential applications in optical communications and imaging.