Tunableness of single-band and dual-band absorption and filtering using vanadium-dioxide-based metamaterial

A single-band and dual-band absorption-to-filter tunable metamaterial is presented in this work, which is formed by a gold ring deposited on dielectric layer, vanadium dioxide (VO${}_2$) plate, and SiO${}_2$ layer. Tunableness from a perfect absorber to filtering is realized using the transition of VO${}_2$ from an insulator to a metallic state. Near-perfect single-band absorption is obtained when VO${}_2$ exhibits the metallic state, while VO${}_2$ is in the insulating state, and the tunableness from absorption to filtering is realized. Both absorption and filtering are attributed to dipole resonances induced by surface plasmon. The positions of the absorption peaks could be controlled under different parameters. Simulation results indicate that width and length of metallic ring are the key factors leading to the frequency shifts of absorption and transmission. Sensing performance of tunable terahertz metamaterial is studied and evaluated, which indicate that refractive index and thickness of the analyte are the main factors causing the shift of the absorption peak and filtering dip, and the sensing sensitivity and figure of merit of the tunable metamaterial are further evaluated. Besides, the effects of absorption and transmission in the case of nested double-ring resonators are investigated. It revealed that dual-band absorption-to-filter switching terahertz functional device is achieved by utilizing the transition of VO${}_2$ from metallic to insulator state. The devices presented here could have excellent properties of high simplification, miniaturization, ease of experimentation, and active modulation, which are of great significance in practical applications.