Influence of micro-structure on modulation properties in VO₂ composite terahertz memory metamaterials

We have grown VO₂ films and combined with terahertz metamaterials to manipulate the memory effect during the insulator-to-metal transition. The temperature-dependent resonant frequency of hybrid structure shows a thermal hysteresis accompanied with frequency shift and bandwidth variation due to the presence of a VO₂ dielectric layer. This frequency memory effect significantly depends on the metallic micro-structure. Further theoretical calculation demonstrates this phenomenon mainly originates from the different coupling strength between VO₂ and metallic structures. Our findings could facilitate the application of VO₂ films in the smart window and dynamical terahertz modulators.