Full-space terahertz metasurface based on thermally tunable InSb

Terahertz (THz) metasurfaces have potential research value in high-quality molecular imaging, high-speed broadband communication, biology, etc. In this paper, thermally tunable full space metasurface was proposed and analyzed by using Finite Difference Time Domain method based on Pancharatnam-Berry phase modulation and InSb temperature characteristic. At 220 K, a metasurface composed of InSb elements can simultaneously achieve efficient transmission and reflection of the incident circularly polarized light at 0.8 THz and 1.15 THz, respectively. On the contrary, at 360 K, the metasurface absorbs all of the incident terahertz waves, essentially turning off the incident beam. In addition, dynamically tunable metalenses were proposed and used to generate focused vortex light. The proposed metasurface provides a potential direction for developing an efficiency-tunable PB terahertz device in the future.