Switchable tri-function terahertz metasurface based on polarization vanadium dioxide and photosensitive silicon.

Area of Science:

• Metamaterials and Nanophotonics
• Terahertz (THz) Technology
• Optoelectronics

Background:

• Metasurfaces offer unique electromagnetic wave manipulation capabilities.
• Dynamic control of terahertz wave properties is crucial for advanced applications.
• Existing metasurfaces often lack multifunctional and reconfigurable features.

Purpose of the Study:

• To propose and demonstrate a novel terahertz switchable metasurface.
• To achieve dual functionalities of polarization conversion and absorption.
• To enable dynamic control over these functionalities using photosensitive silicon.

Main Methods:

• Fabrication of a multilayer metasurface comprising metal patterns, dielectric layers, and a vanadium dioxide (VO2) layer.
• Integration of photosensitive silicon for tunable conductivity.
• Characterization of optical properties under varying VO2 states (insulating and metallic).

Main Results:

• As an insulating VO2 metasurface, it functions as a linear polarization converter with >90% polarization conversion rate (PCR) in two frequency bands (1.64-1.91 THz and 2.35-2.75 THz).
• The metasurface exhibits good asymmetric transmission and dynamically tunable polarization conversion via photosensitive silicon.
• As a metallic VO2 metasurface, it acts as a bidirectional absorber with up to 100% absorptance, showing distinct TE and TM wave absorption controllable by silicon conductivity.

Conclusions:

• The proposed metasurface demonstrates dynamic switching between polarization conversion and absorption functionalities.
• Photosensitive silicon integration allows for real-time control of terahertz wave manipulation.
• Potential applications include dynamic control of polarization waves and near-field image display.