Function switchable broadband wave plate based on the Au-VO₂ hybrid metasurface

Area of Science:

• Optics and Photonics
• Materials Science
• Metamaterials

Background:

• Active materials integrated into metasurfaces enable tunable optical devices.
• Vanadium dioxide (VO2) exhibits a phase transition with temperature, offering tunable properties.

Purpose of the Study:

• To design and demonstrate a switchable multifunctional terahertz metasurface.
• To achieve tunable polarization control using a hybrid gold-vanadium dioxide (Au-VO2) metasurface.

Main Methods:

• Design of an Au-VO2 hybrid metasurface.
• Temperature-dependent characterization of the metasurface's optical response.
• Analysis of electric field and current density distributions to understand physical mechanisms.

Main Results:

• The metasurface functions as a quarter-wave plate (linear to circular polarization conversion) from 0.87-1.2 THz at 298 K.
• At 358 K, it operates as a broadband half-wave plate (0.65-1.45 THz) with chirality preservation and cross-polarization conversion.
• Both functionalities exhibit response efficiencies exceeding 90%.

Conclusions:

• The Au-VO2 metasurface offers switchable quarter-wave and half-wave plate functionalities.
• Tunable geometric phase in the metasurface enables multifunctionality.
• The active metasurface is suitable for tunable terahertz devices manipulating polarization and phase.