Switchable multifunctional meta-structure employing vanadium dioxide in the terahertz range

Abstract

A meta-structure (MS) that can realize a conversion between electromagnetically induced transparency (EIT) and electromagnetically induced absorption (EIA) in the Terahertz (THz) range by utilizing phase-transition vanadium dioxide (VO2) has been reported. This work is controlled by temperature to change the conductivity of VO2 to achieve the switching function. When the VO2 is in the insulator state, the MS is designed to achieve EIT based on the principle of bright mode near-field coupling bright mode. The EIT behavior owns a peak of 0.8 at 0.430 THz with a maximum group delay of up to 6.5 ps. The MS behaves the function of EIA accompanied by the maximum absorption rate of 93.8 % at 0.432 THz while the VO2 film is tuned to the metallic state. The reason for the EIA phenomenon is the magnetic effect of the magnetic dipole generated by the MS in the coupling process. The observed EIT and EIA effects are both theoretically explained by the classic two-oscillator model. In addition, the air columns of the dielectric substrate are utilized for the purpose of frequency approaching. This proposed MS provides a new idea for the design of non-contact regulation and reconfigurable and highly absorbent MSs.