Multi-foci metalens for terahertz polarization detection

Area of Science:

• Optics and Photonics
• Metamaterials
• Terahertz Technology

Background:

• Terahertz (THz) beams possess unique polarization properties crucial for various applications.
• Accurate and compact THz polarization detection remains a significant challenge in the field.
• Existing methods often lack the sensitivity or compactness required for real-world deployment.

Purpose of the Study:

• To design and demonstrate a reflective metalens for versatile THz polarization detection.
• To achieve simultaneous detection of multiple polarization states using a single device.
• To enable precise characterization of THz beam polarization, including handedness, ellipticity, and major axis orientation.

Main Methods:

• Fabrication of a reflective metalens comprising Z-shaped resonators with spatially variant orientations.
• Integration of a reflective gold layer and a dielectric spacer within the metalens structure.
• Utilizing four distinct focal points, each corresponding to a specific polarization state (left circular, right circular, incident, and rotated by π/4).

Main Results:

• The metalens successfully generated four focal points with distinct polarization characteristics.
• Accurate determination of polarization handedness, ellipticity, and major axis orientation was achieved by analyzing light intensities at the focal points.
• The designed metalens demonstrated high performance in characterizing complex THz polarization states.

Conclusions:

• The proposed reflective THz metalens offers a unique and effective solution for compact polarization detection.
• This technology holds significant promise for applications in THz information processing and sensing.
• The ability to determine multiple polarization parameters simultaneously simplifies and enhances THz beam analysis.