A Tunable Ultra-Broadband THz Absorber Based on a Phase Change Material

In this paper, by using a kind of phase change material, a tailored ultra-broadband THz metamaterial absorber is realized, which is based on vanadium dioxide (VO2). Compared with the prior works, the tunable absorption bandwidth can be obtained in the proposed tunable phase change material absorber (TPMA), which can be manipulated by the temperature. The absorption of such a TPMA goes beyond 90% in the frequency region 10.28-15.56 THz and its relative bandwidth is 40.9% when the temperature is equal to or larger than 68 degrees C, and excellent frequency detectability also can be observed. However, when the temperature is less than 68 degrees C, the present TPMA can act as a perfect reflector. The absorption also is investigated for oblique incidence, which shows that the proposed TPMA is incident angle-dependent. The relationships between the structure parameters and the features of absorption also are investigated. The distribution of current surface, the electric field and power loss density are used to elucidate the physical mechanism of such a TPMA. In addition, a reconfigurable device can be realized with such a TPMA by tailoring different temperatures.