Tunable Toroidal Dipolar Resonance for Terahertz Wave Enabled by a Vanadium Dioxide Metamaterial

An active toroidal switch is numerically presented in a terahertz metamaterial. Transmission of toroidal dipole can be tuned by the conductivity of vanadium dioxide, and its modulation depth can be up to 32%. The resonance of toroidal dipole is verified by the distribution of electric current. Due to the unique field distribution of the toroidal mode, the proposed design may find potential applications in enhanced absorption and sensing.