All-dielectric InSb metasurface for broadband and high-efficient thermal tunable terahertz reflective linear-polarization conversion

In this paper, an all-dielectric InSb metasurface (MS) is proposed and investigated in terahertz (THz) regime, which can achieve broadband thermal tunable reflective linear-polarization (LP) conversion. The unit-cell of the proposed MS is composed of a single anisotropic InSb micro-cuboid structure adhered on an continuous InSb film. The electric property of the InSb can be tuned actively by changing the environment temperature. Under room temperature (295 K), the proposed InSb MS can reach a high cross-polarization reflection coefficient over 90 %, and the polarization conversion ratio (PCR) over 95% on average from 1.21 THz to 1.92 THz with the relative bandwidth of 45.4%. It means that the designed InSb MS can convert the LP wave into its orthogonal component after reflection in a broadband range at a given external temperature. The physical insights behind perfect LP conversion is explored by analyzing the induced electric field distributions in unit-cell of the designed InSb MS. Furthermore, the broadband LP conversion property of the InSb MS can be tuned easily by changing surrounding temperature. The simple geometry and the higher performance of the proposed InSb MS can be found potential applications in many areas, such as sensors, reflector antennas, and radiometers in THz regime.