Thermally and magnetically controlled dual-band terahertz metamaterial absorber based on InSb

Abstract

A thermally and magnetically controlled dual-band terahertz metamaterial absorber with a simple structure consisting of a patterned InSb film, a Teflon dielectric layer, and a metal board is designed and investigated. Numerical simulation results demonstrate that the absorption peak can reach 94% at 0.434 THz and 0.692 THz at 300 K, in the absence of an applied magnetic field. The absorber has the features of polarization insensitivity due to the symmetry of the structure and wide incidence angle absorption. The physical absorption mechanism can be analyzed by the impedance matching theory, the electric field distribution, the current distribution, and the excitation of LC resonance theory. Furthermore, the metamaterial absorber enables temperature-tunable characteristics due to the temperature-dependent variation of the permittivity of InSb in the terahertz region. By varying temperature from 295 to 320 K, the first resonance frequency gradually shifts from 0.413 to 0.529 THz with the second peak shifting from 0.654 to 0.863 THz. In addition, frequency dependent absorption of the InSb-based metamaterial absorber under a series of applied magnetic fields is discussed. When the magnetic field B is changed from 0.2 T to 1T, the dual resonant frequencies gradually shift from 0.4816 THz to 0.423 THz and 0.7804 THz to 0.716 THz. The InSb pattern film behaves as a resonant unit, thus providing an alternative method for designing independent bi-tunable absorbers in the terahertz band. The proposed absorber has the advantages of good tunability, simple structure, and high sensitivity, which has great potential in terahertz sensors. This work provides an effective method for implementing thermally and magnetically dual-controlled terahertz metamaterial absorbers.