Reconfigurable terahertz-infrared absorber enabled by MEMS actuation and VO₂ phase transition

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Terahertz (THz) and infrared (IR) absorbers are crucial for applications like sensing and stealth.
• Existing absorbers often lack tunability or reconfigurability.
• Vanadium dioxide (VO2) and graphene offer unique phase transition and electronic properties for tunable devices.

Purpose of the Study:

• To propose and demonstrate a reconfigurable THz-IR absorber.
• To achieve switchable amplitude and frequency tuning functionalities.
• To leverage boundary-condition-controlled mode switching in a MEMS-enabled VO2-graphene Fabry-Pérot architecture.

Main Methods:

• Fabrication of a MEMS-enabled VO2-graphene Fabry-Pérot device.
• Utilizing the phase transition of VO2 (insulating to metallic state).
• Investigating two distinct resonance families: lateral Fabry-Pérot (L-FP) and quasi-vertical Fabry-Pérot (QV-FP) modes.

Main Results:

• The VO2 phase transition selectively activates L-FP and QV-FP resonances.
• L-FP modes show high absorptance modulation (99.2%) with frequency insensitivity.
• QV-FP modes exhibit significant frequency tuning (79.0%) with high peak absorptance (99.996%).

Conclusions:

• Boundary-dependent mode switching enables multifunctional THz-IR absorption.
• The proposed architecture provides a versatile strategy for reconfigurable optical devices.
• This work paves the way for advanced tunable THz-IR applications.