Narrow-broadband switchable THz absorber based on graphene and VO₂

Area of Science:

• Electromagnetics
• Materials Science
• Condensed Matter Physics

Background:

• Terahertz (THz) waves have unique properties like penetration and high capacity, making THz absorption significant.
• Previous research focused on narrowband or broadband THz absorbers.
• Adjustable and switchable THz absorption remains a key research challenge.

Purpose of the Study:

• To develop a THz absorber with switchable narrowband and broadband absorption capabilities.
• To utilize the tunable properties of graphene and the phase transition of vanadium dioxide (VO2) for adjustable absorption.
• To investigate the absorption characteristics under different conditions.

Main Methods:

• Fabrication of a THz absorber incorporating graphene and vanadium dioxide (VO2).
• Characterization of absorption spectra in both insulating and conductive states of VO2.
• Analysis of the absorber's performance concerning temperature, VO2 properties, and incidence angle.

Main Results:

• The absorber exhibits dual narrowband absorption (near 100%) when VO2 is in its insulating state.
• Upon heating, VO2 transitions to a conductive state, enabling ultra-wideband absorption (2.24 THz bandwidth).
• The broadband mode demonstrates robustness to VO2 relaxation time and thickness variations, and is insensitive to incidence angle.

Conclusions:

• A novel narrow-to-wideband switching THz absorber has been successfully demonstrated.
• The proposed absorber offers tunable and switchable absorption characteristics, leveraging graphene and VO2.
• This work provides new insights for advanced THz applications and metamaterial absorber research.