Active terahertz nanoantennas based on VO₂ phase transition

Unusual performances of metamaterials such as negative index of refraction, memory effect, and cloaking originate from the resonance features of the metallic composite atom^1-6. Indeed, control of metamaterial properties by changing dielectric environments of thin films below the metallic resonators has been demonstrated^7-11. However, the dynamic control ranges are still limited to less than a factor of 10,^7-11 with the applicable bandwidth defined by the sharp resonance features. Here, we present ultra-broad-band metamaterial thin film with colossal dynamic control range, fulfilling present day research demands. Hybridized with thin VO₂ (vanadium dioxide)^12-18 films, nanoresonator supercell arrays designed for one decade of spectral width in terahertz frequency region show an unprecedented extinction ratio of over 10000 when the underlying thin film experiences a phase transition. Our nanoresonator approach realizes the full potential of the thin film technology for long wavelength applications.