Asymmetric Fabry-Pérot cavities for thermally tunable multimode perfect THz absorption

Area of Science:

• Metamaterials
• Terahertz (THz) technology
• Optical physics

Background:

• Terahertz (THz) absorbers are crucial for 6G communications, imaging, and sensing.
• Existing THz absorbers face challenges with bandwidth, tunability, and robustness.
• Coupled trade-offs limit practical applications of current THz absorber designs.

Purpose of the Study:

• To propose a dual-functional-layer metamaterial absorber.
• To overcome limitations of single-layered designs and coupled trade-offs.
• To achieve reconfigurable absorption characteristics with wide-angle and polarization insensitivity.

Main Methods:

• Utilized a periodically patterned vanadium dioxide (VO2) layer and a continuous VO2 film.
• Formed an asymmetric Fabry-Pérot (F-P) cavity with a metallic backplane.
• Employed finite-element simulations and the Drude model for VO2 conductivity.

Main Results:

• Achieved near-perfect absorption (>90%) from 3.25-16.56 THz in the metallic state.
• Demonstrated switchable absorption modes: ultrabroadband, dual-band (2.15-6.17 THz & 11.75-16.52 THz), and narrowband (~99.98% peak).
• Exhibited polarization insensitivity (0-90°) and high absorption up to 60° incidence.

Conclusions:

• The proposed dual-layer metamaterial absorber offers multifunctional THz absorption.
• The design provides a compact and reconfigurable solution for adaptive THz systems.
• This work advances THz absorber technology for diverse applications.