Polarization-insensitive broadband terahertz absorber using graphene-vanadium dioxide phase change material

• The research focuses on a graphene metamaterial that incorporates vanadium dioxide (VO 2 ) to leverage its phase change properties, enhancing the optical characteristics. • VO 2 allows for temperature-dependent transitions between dielectric and metallic states, facilitating dynamic tuning of the absorption properties. • The proposed architecture achieves an absorption bandwidth of 7.69 THz and absorption rates exceeding 90%, peaking at 95%, showcasing high efficiency for THz applications. • The design demonstrates insensitivity to polarization in both TE and TM modes, ensuring reliable performance across various spectral ranges. • Despite the promising outcome, the ability to adjust the spectral absorption response post-fabrication presents a significant challenge for practical implementations in THz technologies. We present an effective mechanism of a graphene based metamaterial for THz absorption, utilizing the outstanding optoelectronic characteristics of graphene alongside metamaterials. By conducting extensive numerical simulations of five structural configurations, we chose an optimised design that features the phase change material vanadium dioxide (VO 2 ). The incorporation of phase change material like VO 2 , which demonstrates a transition between dielectric and metallic states, offers a viable approach for dynamically regulating optical properties based on temperature, thus improving the flexibility and capability of THz absorbers. This architecture achieves an enhanced absorption bandwidth of 7.69THz, absorption rates surpassing 90% (peaks at 95%). The proposed absorber’s tunability allows for dynamic adjustment of absorption frequency, which is crucial for sophisticated applications in the above mentioned THz imaging, sensing, and communication technologies. We have also examined its polarization insensitivity in TE and TM mode. Its capability for broad absorption ensures reliable performance across a large spectral range, meeting the need for high efficiency THz devices. Resonant absorbers that incorporate plasmonic materials and thin film structures facilitate spectrally selective absorption, where maximum absorption occurs at defined resonance wavelengths. Resonant absorbers can be engineered to operate across diverse spectral regimes for applications in thermal emission, thermophotovoltaics, sensing and absorption filtering. However, the tunability of the spectral absorption response after fabrication remains a significant challenge.