Effect of Unit Cell Shape on Switchable Infrared Metamaterial VO₂ Absorbers/Emitters

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Metamaterials offer unique ways to control infrared radiation.
• Switchable absorbers/emitters are crucial for adaptive infrared systems and sensing.

Purpose of the Study:

• To propose and analyze novel, simple switchable infrared metamaterial absorbers/emitters.
• To investigate the influence of unit cell geometry (triangle, square, hexagon, circle) on performance.

Main Methods:

• Numerical simulations were performed using Ag/VO₂ disks on an Ag plane.
• The optical properties were analyzed across different VO₂ states (insulating and metallic).
• Electromagnetic field distributions were studied to understand absorption mechanisms.

Main Results:

• High spectral absorption peaks (>0.99) were achieved at ~4 μm for the insulating VO₂ state.
• Absorption peaks vanished when VO₂ transitioned to the metallic state, enabling switching.
• Magnetic polariton excitation in the VO₂ layer was identified as the primary absorption mechanism.
• Square and circular unit cells demonstrated polarization-independent absorption (0°-90°).
• All designs showed stable performance under varying incident angles.

Conclusions:

• The proposed metamaterials function as effective switchable infrared absorbers/emitters.
• The design demonstrates tunability via the VO₂ phase transition.
• These devices hold potential for applications in sensing technology and adaptive infrared systems.