Switchable Metamaterial with Terahertz Buffering and Absorbing Performance

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 function-switching metamaterial which provides potential applications in terahertz detecting, switching and slow light devices.