Helicity-switched hologram utilizing a polarization-free multi-bit coding metasurface.

Area of Science:

• Electromagnetics
• Metamaterials
• Wave Manipulation

Background:

• Traditional Pancharatnam-Berry phase metasurfaces exhibit anti-symmetrical responses for orthogonal circularly polarized states.
• This asymmetry leads to polarization-conversion losses and limits identical functionality for both right-handed and left-handed circularly polarized waves.

Purpose of the Study:

• To propose and demonstrate a polarization-free coding metasurface.
• To enable identical manipulation of both right-handed and left-handed circularly polarized waves.
• To overcome limitations of conventional metasurfaces regarding polarization-dependent responses.

Main Methods:

• Design of a polarization-free coding metasurface architecture.
• Implementation of multi-bit coding for advanced wave control.
• Fabrication and experimental validation of a prototype metasurface.

Main Results:

• Demonstration of identical functionality for both right-handed and left-handed circularly polarized waves.
• Achieved helicity-switched holograms in the microwave region.
• Experimental validation showed high imaging efficiency (>76%) at 10 GHz for arbitrary polarizations.

Conclusions:

• The proposed polarization-free metasurface offers enhanced control over circularly polarized waves.
• This design overcomes polarization-conversion losses and provides an additional degree of freedom in handedness control.
• The method is applicable across the electromagnetic spectrum for versatile wavefront manipulation.