Transmission and reflection bi-direction terahertz encoding metasurface with a single structure.

Area of Science:

• Metasurfaces
• Terahertz Technology
• Phase Change Materials

Background:

• Existing metasurfaces typically operate in a single mode (transmissive or reflective), limiting practical applications.
• Dynamic control over metasurface operation is crucial for advanced functionalities.

Purpose of the Study:

• To propose and demonstrate a bi-directional operation coding metasurface.
• To achieve dynamic switching between transmissive and reflective modes using vanadium dioxide (VO2).

Main Methods:

• Designed a metasurface structure incorporating silicon columns, a polyimide dielectric substrate, and a VO2 film.
• Utilized the temperature-dependent phase transition of VO2 (dielectric to metallic state) to control metasurface functionality.
• Investigated terahertz wave manipulation in both transmission and reflection regimes.

Main Results:

• The metasurface demonstrated transmission beam splitting, deflection, and vortex beam generation in the dielectric state of VO2.
• In the metallic state of VO2, it exhibited reflection beam splitting, deflection, radar scattering surface (RCS) reduction, and vortex beam generation.
• Successfully achieved dynamic, invertible switching between transmissive and reflective modes by altering ambient temperature.

Conclusions:

• The proposed VO2-assisted metasurface offers bi-directional terahertz encoding regulation, overcoming limitations of single-mode devices.
• This work presents a new pathway for developing multi-functional terahertz devices with tunable properties.