3D-printed mirror-less helicity preserving metasurface "mirror" for THz applications

Area of Science:

• Metasurfaces and wave control
• Terahertz (THz) technology
• Optics and photonics

Background:

• Metasurfaces enable advanced wave manipulation with optically thin structures.
• Terahertz (THz) regime applications are growing in communication and sensing.
• Generalized reflection and refraction laws inspire new metasurface designs.

Purpose of the Study:

• To propose a simple THz metasurface design for specific polarization control.
• To demonstrate perfect cross-polarized and helicity-preserving reflection without a back-reflector.
• To explore applications in beam steering, focusing, and molecular chirality sensing.

Main Methods:

• Numerical simulations to model metasurface response.
• Analytical models to provide physical insights.
• Fabrication via direct laser writing 3D printing and silver plating.
• Characterization using THz time-domain spectroscopy.

Main Results:

• Achieved ideally perfect cross-polarized reflection for linear polarization.
• Demonstrated perfect helicity-preserving reflection with geometric (Pancharatnam-Berry) phase for circular polarization.
• Experimental results validated theoretical predictions.
• Numerical demonstration of beam steering, focusing, and potential in chirality sensing.

Conclusions:

• The proposed THz metasurface design offers efficient and versatile polarization control.
• Direct laser writing and silver plating provide a viable fabrication route.
• The metasurface's helicity-preserving mirror property is valuable for sensing applications, particularly molecular chirality.
• The study validates analytical models and experimental findings, paving the way for practical THz devices.