Terahertz (THz) Metasurface Switch by Phase Change Medium

As the two dimensional (2D) counterpart of metamaterial, metasurface is actually an ultra-thin planar array of sub-wavelength elements based on the generalized Snell's Law. In addition, phase change material, e.g. the Ge
₃
Sb
₂
Te
₆
(GST), emerges as a special medium with an ability to reversibly switch between the amorphous and crystalline states by thermal or electrical control. In this paper, by combing the functionalities of metasurface and GST together, a THz switch is presented by constitution of an active or tunable metasurface. Our results indicate that two states of the phase change dielectrics induce the obvious transition of its electromagnetic properties and thus prominent shift of resonant frequency, i.e. 28.28%. Further, the achieved peak absorption is 99.66% and 88.59% at two thermally switched states, so as to create a THz photonic switch of tunable metasurface by distinctly varied absorption at different resonant frequencies.