Thermally Tunable Terahertz Bifunctional Metasurface Based on Indium Antimonide

A metasurface with thermal tunability using Indium Antimonide (InSb) is proposed, showing dual functionalities of absorption and polarization conversion. In its metallic state at a temperature of 280K, the system operates as a single-band absorber, exhibiting a peak absorptance of 100% at the frequency of 0.408 THz which is composed of a InSb square with a cross-shaped hole array, a silica $(\text{SiO}_{2})$ substrate, and a InSb film. It holds broad applicability for band-stop THz filters. In the insulating state of InSb at a temperature of 200K, the system functions as a cross-polarization converter, adept at transforming linear plane waves into their corresponding cross-polarized counterparts with high efficiency in the frequency range of 0.6-0.8 THz, composed of a one-dimensional gold (Au) strip array, a $\text{SiO}_{2}$ substrate, and a gold (Au) film. The proposed metasurface emerges as a promising candidate for contemporary devices focused on polarization control.