Broadband high-absorption tunable terahertz metamaterial absorber integrating gallium arsenide and vanadium dioxide

Since terahertz waves couple weakly with samples in free space and conventional metal/dielectric metamaterial structures cannot be tuned after fabrication, which limits trace detection and real-time frequency control, there is a pressing need for a single-structure solution that enables broadband, dynamically tunable, multi-resonant absorption. In this paper, we propose a semiconductor-tunable terahertz metamaterial absorber based on gallium arsenide (GaAs) and vanadium dioxide (VO 2 ). By incorporating and replacing GaAs and VO 2 materials, the absorber achieves dynamic tunability within the frequency range of 0.5-2.0 THz. The absorptivity reaches 98.7% when GaAs is solely employed for modulation and further increases to 99.2% when both GaAs and VO 2 are utilized simultaneously. Detailed simulation and theoretical analysis of the resonance mechanisms have been conducted. The results reveal that the variation of group delay in the slow-light effect closely follows the changes observed in the absorption spectrum of the structure. Owing to its broadband, high absorptivity, and real-time tunability, the proposed metamaterial absorber shows great potential for applications in terahertz functional devices.