High-performance terahertz absorber with tunable and ultra-broadband characteristics based on synthetic- patterned vanadium dioxide metamaterials

Abstract In this paper, we designed a terahertz absorber based on vanadium dioxide (VO2) with tunable and ultra-broadband characteristics. The absorber is composed of four identical synthetic VO2 patterns, the dielectric layer and the metal reflector layer from top to bottom. The results indicate that the designed absorber achieves essentially total reflection when VO2 is in the insulated state. The designed absorber has an absorption bandwidth of over 90% absorptance up to 7.7 THz in the frequencies range 5.36 THz-13.06 THz when VO2 is in the metallic state. By adjusting the conductivity of VO2, the absorber realizes near-perfect amplitude modulation with absorbance dynamically tuned from 4.31% to 100%. The operating principle of ultra-broadband absorber is interpreted by wave interference theory, impedance matching theory and electric field analysis, respectively. Compared to previously reported terahertz absorbers, the designed absorber offers significant improvements in the absorption broadband, and it also has many advantages such as simple structure, polarization insensitivity, and flexible incident angle. Such tunable ultra-broadband terahertz absorbers hold great promise in the fields of photochemical energy absorption, thermal emitters, and stealth.