Dual-frequency multi-function switchable metasurface

Abstract

Most metasurfaces can manipulate electromagnetic waves in the deep sub-wavelength range, but often have the disadvantages of low modulation depth and single-frequency operation. Here, a vanadium dioxide composite aluminum antenna (VCAA) for dual-frequency switchable function is proposed. After the vanadium dioxide (VO2) phase transition, the VCAA can achieve a high reflection coefficient (about 0.78) and 2π phase coverage independently at different frequencies under circular polarization (CP) incidence by rotating double C-type resonator and double D-type resonator. In order to better understand this characteristic, the surface electric field distribution of the metasurface is calculated and analyzed. Three temperature-switchable metasurfaces with beam splitting, focusing (divergence) and vortex beams functions at different frequencies are designed by encoding different arrangements of particles and convolution operations. And these functions are not influenced by the temperature at 0.52 THz, but have the effect of temperature-switchable at 0.98 THz. The functions of these three metasurfaces are demonstrated and verified from the perspective of electric field and phase. This work provides a new method for the dynamic regulation of terahertz waves and the design of multi-frequency devices, and accelerates the development of terahertz communications and information encryption.