Design of a tunable multiband terahertz waves absorber

A thermally tunable multiband terahertz metamaterial absorber comprising a periodic array of closed metallic square ring resonators and four metal bars parallel to the four side of the square ring, fabricated on the low-temperature co-fired ceramic (LTCC) strontium titanate (STO) dielectric layer dielectric substrate has been proposed. The resonance frequencies of the absorber are demonstrated to be continuously tuned in the terahertz regime by increasing the temperature. It is found that in the window between 0.05 and 0.35 THz the absorber has three distinctive absorption peaks at frequencies 0.129 THz, 0.198 THz and 0.316 THz (at the room temperature), whose peaks are attained 99.3%, 99.1% and 94.6% respectively. The tunability is attributed to the temperature-dependent permittivity of the substrate and attained to 67.3% frequency tuning depth at the room temperature, when the temperature varied from 400 K to 200 K. The proposed designs ensure broadband thermally tunable terahertz devices.