Switchable trifunctional terahertz absorber for both broadband and narrowband operations

Area of Science:

• Optics and Photonics
• Materials Science
• Electrical Engineering

Background:

• Terahertz (THz) absorbers are crucial for THz applications.
• Achieving tunable and switchable absorption remains a challenge.

Purpose of the Study:

• To propose a multilayer THz absorber with switchable absorption states.
• To investigate the tunability using graphene and vanadium dioxide (VO2).

Main Methods:

• Fabrication of a hybrid graphene-VO2 multilayer structure.
• Electrical tuning of graphene's Fermi level.
• Thermal tuning of VO2 phase transition (metal-insulator).

Main Results:

• Demonstrated three distinct switchable absorption states.
• Achieved high-frequency broadband absorption (5.45 THz) with VO2 in metal phase and graphene at 0 eV.
• Observed switchable low-frequency broadband (2.86 THz) and dual-frequency absorption by tuning graphene's Fermi level with VO2 in insulator phase.

Conclusions:

• The proposed absorber offers versatile, multi-state THz absorption.
• Potential applications in THz modulators, filters, and detectors.