A visible-near infrared wavelength-tunable metamaterial absorber based on the structure of Au triangle arrays embedded in VO₂ thin film

We propose a metamaterial electromagnetic wave absorber which is aimed to achieve the wide tunability of resonance absorption peak in visible and near-infrared (NIR) regime. The metamaterial absorber consists of Au triangle nanoparticle arrays, vanadium dioxide (VO₂) film dielectric layer and the gold reflective layer, and the Au triangle arrays are embedded in the VO₂ film. We explore the change of resonance wavelengths affected by the thickness of the VO₂ dielectric layer. When the thickness of VO₂ film is 90 nm, the absorption peak achieves a large tunability of 56.2% while the VO₂ undergoes a structural transition from metallic phase (m-VO₂) to insulator phase (i-VO₂). The large wavelength tunability can be explained by a hybrid electric resonance and magnetic resonance mode from the electromagnetic field distributions at the resonance wavelengths. The absorbers with tunable resonance wavelengths would be beneficial to the sensor and detector applications in terms of heat or light signal.