Transformation of Broadband Absorption to Electromagnetically-Induced Transparency Utilizing Terahertz Metamaterial-Based Phase Change Vanadium Dioxide

A functionally switchable terahertz metamaterial based on phase change materials to realize broadband absorption to electromagnetically-induced transparency is proposed, consisting of a surface structure of vanadium dioxide (VO₂) and Au placed on a continuous VO₂ film separated by a dielectric layer using polyimide. When the VO₂ is in the metallic state, the terahertz metamaterial is in the broadband absorption mode, achieving near-perfect absorption at 0.77 THz, 1.14 THz, and 1.66 THz, with more than 90% of the absolute absorption bandwidth reaching 1.08 THz, and the relative absorption bandwidth is 87.10%. When VO₂ is in the dielectric state, the given device is in the electromagnetically induced transparency mode, with two dips at 0.95 THz and 1.56 THz, and a transparency window at 1.24 THz, with a maximum group delay of up to 6.21 ps. The maximum modulation amplitude can reach 90.67% and 84.24% in both modes, and good robustness could be maintained in both modes when the polarization angle was not more than 40° and the incidence angle was not greater than 40°. Our proposed terahertz metamaterial with functionally switchable is expected to be promising in the fields of terahertz imaging, sensing, and slow light devices.