Dynamically Switchable Sub-THz Absorber Using VO $_{2}$ Metamaterial Suitable in Optoelectronic Applications

Temperature-sensitive materials are known as phase change materials (PCMs) which has transition between two different states. Dynamically tunable devices can be designed utilizing these materials. Vanadium dioxide (VO $_{2})$ considered as a PCM material which transits from the insulator state to the metal one by increasing the temperature. VO $_{2}$ has recently been utilized to design tunable absorbers. In this article, we presented a dual-band absorber structure design which consist of double arrays of VO $_{2}$ ring-based placed on top of a dielectric buffer/spacer terminated with a conducting layer acting as a back reflector. Each ring acts as a resonator producing a surface plasmon resonance (SPR). Having a proper unit cell design with an appropriate dimension, a dual-band absorber with an absorption amplitude above 95% (on state) can be achieved at terahertz (THz) frequency range in the metallic state; whereas the absorption value is 0.6% (off state) in the insulator state of VO $_{2}$ . Therefore, the proposed structure design has the possibility to switch between these two on/off states by changing the material's temperature. The interference theory and the equivalent circuit model are investigated to verify the achieved result using high-frequency structure simulator (HFSS) software which works based on finite element method (FEM). This structure has the potential optoelectronic applications such as refractive index (RI) optical sensing and biomedical detection, photonics detectors, and optical storage applications.