Terahertz Metamaterial Based on Controllable Electromagnetic Induced Transparency Structure

Based on the tunable conductivity of semiconductor silicon, a controllable electromagnetic induced transparency (EIT) structure composed of cut wires (CW) and split-ring resonators (SRR) is designed, and the active modulation of EIT effect is realized. It is found that a narrow transparency window with a transmittance of about 94% appears in the transmission spectrum at near 1.33 THz when the conductivity of semiconductor silicon was 1 Sim. When the conductivity increases to 5000 S/m, the transmittance becomes 58% and when the conductivity approaches 15000 S/m, the EIT effect almost disappears, and the modulation efficiency approaches 66%. The transmission spectra under different conductivities are consistent with their fitting curves by the coupled mode theory, indicating that the simulation results are in accord with the theoretical calculation findings. Both the simulation and calculation results show that the damping ratio of dark mode and the loss increase when the electrical conductivity of silicon increases. When the electrical conductivity reaches a certain value, the resonance of dark mode is not be stimulated and thus the EIT effect disappears.