Electric dipole resonance-driven terahertz broadband absorber with wide-angle and dynamic tunability

Abstract

To address the challenges of limited bandwidth and structural complexity in terahertz absorbers, this study proposes a vanadium dioxide (VO₂)-based broadband terahertz (THz) absorber driven by electric dipole resonance. The device achieves broadband absorption exceeding 90% within 3.55–9.95 THz, an absorption bandwidth of 6.4 THz and a fractional bandwidth reaching 94.81%. Through comprehensive analyses including impedance matching theory, multiple reflection interference theory, multipole decomposition, and electric field distribution, we confirm that the broadband absorption mechanism originates from electric dipole resonances excited at the structural edges of VO₂. Furthermore, the temperature-controlled phase transition properties of VO₂ enable dynamic tuning capability. The devices exhibit excellent polarization insensitivity and wide-angle stability with a synergistic effect of structural symmetry and slit design, and maintain efficient broad absorption at 40° incidence. Finally, the devices were found to have good process tolerance by varying different structural parameters. This work provides a high-performance and integration-friendly solution for THz metamaterial absorbers, showing significant application potential in electromagnetic shielding, smart switching, and wavefront modulation.