Switchable Metamaterial With Terahertz Buffering and Absorbing Performance

Abstract

A terahertz metamaterial with switching characteristics from optical buffering to absorbing performance is realized by incorporating a phase-change film of vanadium dioxide. By introducing the electromagnetically induced transparency behavior based on simple strip pairs, the slow light effect with group delay up to 3.5 ps is obtained. When vanadium dioxide is in the insulator state, the remarkable delay can be observed as the incident pulse transmits through the designed structure. Once the vanadium dioxide film is tuned to the metallic state, the metamaterial is switched to a terahertz absorber and the maximum absorption rate of 94% is observed at 1.04 THz. The switching mechanism is discussed by analyzing the electric field and power loss distributions, as well as the impedance matching principle. Moreover, the buffering capability and the absorption performance both remain noticeable within a wide range of the incidence angle. This work offers a strategy for the functionswitching metamaterial which provides potential applications in terahertz detecting, switching and slow light devices.

Switchable Metasurface with Electromagnetically Induced Transparency and Absorption Simultaneously Realizing Circular Polarization‐Insensitive Circular‐to‐Linear Polarization Conversion

“…Since the VO 2 acts as a common dielectric, it owns little impact on the EIT in the generation of transparency windows. [ 45 ] More importantly, since the IRR and ORR are centrosymmetric for both y ‐ and x ‐polarized waves, the rings are polarization insensitive for both these two polarization waves. Similarly, it is the same for LCP waves and RCP waves.…”

“…As for the transmission peak (1.130 THz), the SCDs are distributed on both the ORR and IRR, which are almost opposite in Figure 3c. The ORR and IRR are concurrently induced because of the resonance detuning, [ 45 ] indicating the destructive interference between the two bright modes. This phenomenon greatly illustrates the formation of the EIT transparent window in Figure 2c.…”

“…The EIA can be effectively observed due to the constructive interference between the near‐field coupled rings. The frequency‐dependent absorbance of the MS can be calculated under the RCP waves incidence as follows [ 45 ] $$\begin{eqnarray} A(\omega ) &=& 1 - {\left| {{R_{{\rm{RCP}} - {\rm{RCP}}}}(\omega )} \right|^2} - {\left| {{R_{{\rm{RCP}} - {\rm{LCP}}}}(\omega )} \right|^2}\nonumber\\ && - \left| T_{{\rm{RCP}} -\ {\rm{RCP}}}(\omega ) \right|^2 - {\left| {{T_{{\rm{RCP}} - {\rm{LCP}}}}(\omega )} \right|^2} \end{eqnarray}$$where R RCP‐RCP and R RCP‐LCP respectively refer to the main polarization and crosspolarization reflection coefficients. Similarly, T RCP‐RCP and T RCP‐LCP refer to the main polarization and crosspolarization transmission coefficients, respectively.…”

“…When the VO 2 is in the insulator state, relative permittivity and conductivity are designed as 12 and 200 S m −1 , respectively. [ 45,69 ] On the contrary, while the VO 2 is in a metallic state, the corresponding conductivity is 3 × 10 5 S m −1 . [ 45,69 ] Eventually, we use the software high frequency structure simulator (HFSS) to simulate our MS.…”

“…[ 45,69 ] On the contrary, while the VO 2 is in a metallic state, the corresponding conductivity is 3 × 10 5 S m −1 . [ 45,69 ] Eventually, we use the software high frequency structure simulator (HFSS) to simulate our MS.…”