Active Terahertz Nanoantennas Based on VO₂ Phase Transition

TLDR

Metamaterials achieve effects such as negative refraction, memory, and cloaking through resonant metallic composites, but dynamic tuning via dielectric environments remains limited to less than a ten‑fold change and narrow bandwidths. This work introduces an ultra‑broadband metamaterial thin film that offers a colossal dynamic control range to meet current research needs. When combined with VO₂ thin films, the nanoresonator supercell arrays span a one‑decade terahertz bandwidth and achieve an extinction ratio exceeding 10,000 during the VO₂ phase transition, demonstrating the full potential for long‑wavelength applications.

Abstract

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 VO(2) (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.