A study on the electromagnetic mechanism of a flexible terahertz toroidal dipole metasurfaces

Abstract

We have designed and fabricated metasurfaces structures generated toroidal dipole phenomenon by fabricating periodic metal pattern on polyimide substrate. The metasurfaces structure consists of two symmetric split rings along the Y-axis. The impact of structural parameters, gap, and SR, on the electromagnetic characteristics of metasurfaces at terahertz frequencies was investigated. An increase in gap results in a blue shift phenomenon in the amplitude transmission spectrum, while an increase in SR leads to a red shift phenomenon in the amplitude transmission spectrum. The intrinsic mechanism of the toroidal resonance is investigated more deeply by calculating the multipole scattering power and Q-factor. Q-factor values of 2.3 and 9.5 were obtained at low and high frequencies, respectively. Terahertz toroidal dipole metasurfaces made on flexible substrates like this have the potential for applications in terahertz functional devices, such as sensors and tuners.