Broadband and high modulation-depth THz modulator using low bias controlled VO₂-integrated metasurface

Area of Science:

• Metamaterials
• Condensed Matter Physics
• Optics and Photonics

Background:

• Terahertz (THz) wave modulation is crucial for advanced optical systems.
• Vanadium dioxide (VO2) exhibits a phase transition that can be exploited for tunable devices.
• Metasurfaces offer precise control over electromagnetic waves.

Purpose of the Study:

• To demonstrate an active vanadium dioxide integrated metasurface for broadband THz wave modulation.
• To achieve large modulation depth under electrical control.
• To investigate the mechanism behind the electrical tunability.

Main Methods:

• Fabrication of a metasurface with grid-structure patterned VO2 film on a sapphire substrate.
• Integration of metal bias-lines for electrical control.
• Characterization of amplitude transmission across a broad THz frequency range (0.3-1.0 THz).

Main Results:

• Continuous amplitude transmission tuning from over 78% to 28% was achieved.
• A large modulation depth exceeding 87% over a 0.7 THz bandwidth was demonstrated.
• The electrical tunability was attributed to ohmic heating effects.

Conclusions:

• An active VO2 integrated metasurface provides broadband THz wave modulation with high modulation depth.
• Electrical control via ohmic heating enables tunable THz transmission.
• The device shows significant potential for applications like tunable THz attenuators.