Tunable conversion of electromagnetically induced transparency to electromagnetically induced absorption based on vanadium dioxide metastructure

Metastructure analogs of electromagnetically induced transparency (EIT) show great potential in telecommunications, light storage, and slow light, owing to the unremitting research of our predecessors. Research on electromagnetically induced absorption (EIA) has also been accelerating in recent years. However, few researchers have studied the switch between the EIT and EIA. This paper proposes a tunable conversion of EIT to EIA in the terahertz (THz) band, by employing vanadium dioxide (VO2), a phase change material. With the incidence of the electromagnetic wave, the split-ring resonator is coupled with a double U-shaped resonator when VO2 is set in the dielectric state, and destructive interference appears, resulting in EIT. The cross-shaped resonator works when VO2 functions in the metallic state, which allows coherence enhancement, and the EIA phenomenon can be observed. Moreover, the value of the maximum transmission coefficient reaches 0.837 at 0.570 THz with maximum group delay reaching up to 4.45 ps through calculation, proving the slow light effect of EIT. In the metallic state of VO2, the maximum absorption value arrives at 0.826 at 0.571 THz. The consistency of the simulation results is further confirmed by verifying the dual spring vibration model. © 2023 Elsevier GmbH