Study on a terahertz modulator based on metamaterial with photoinduced vanadium dioxide film

Abstract

Applying the photoexcitation characteristics of vanadium dioxide (VO₂), a dynamic resonant terahertz (THz) modulation with the combination of a VO₂ film and a metamaterial was suggested to realize THz wave active manipulation. The designed metamaterial with structured copper rings arrays can realize a passband from 0.776 to 1.045 THz. When insulator–metal phase transition in VO₂ thin film, which is deposited on the other surface of the metamaterial substrate, is induced by optical pumping, the metamaterial/VO₂ film hybrid structure behaves as an absorber with absorption rates of 90% at 0.88 THz and the transmission energy decrease to less than 3%. Therefore, about 78% modulation depth and more than 250 GHz modulation bandwidth have been reached under the photoinducing. The simulation results illustrate the promise of using phase transition materials for efficient broadband fast response modulators for THz waves.