Active control of electromagnetically induced transparency based on vanadium dioxide microstructures

Electromagnetically induced transparency (EIT) based on metasurfaces has made significant advancements in the past decade. The ability to actively tune EIT is desirable for practical applications, and this has been accomplished by integrating metallic structures with tunable materials. Here, we propose a dynamically tunable EIT using a metasurface composed of vanadium dioxide (VO2) microstructures without additional metallic structures. A single cut wire and a pair of U-Shape split ring microstructures are combined to design the unit cell of the VO2 metasurface, which functions as bright and dark modes, respectively. The destructive interference between these two modes causes an EIT-like resonance at the terahertz band for VO2 in its metallic phase. However, when VO2 transitions into its insulating phase, the EIT resonance gradually vanishes. Theoretical analyses based on the electric field distribution and coupled harmonic oscillator model indicate that the tunable EIT is due to changes in the attenuation rate of two modes. Furthermore, the phase transition of VO2 can generate tunable group delays. The active EIT utilizing VO2 microstructures could be applied in terahertz modulators and tunable slow light devices.