Abstract
Polarization manipulations of electromagnetic waves can be obtained by chiral and anisotropic metamaterials routinely, but the dynamic and high-efficiency modulations of chiral properties still remain challenging at the terahertz range. Here, we theoretically demonstrate a new scheme for realizing thermal-controlled chirality using a hybrid terahertz metamaterial with embedded vanadium dioxide (VO2) films. The phase transition of VO2 films in 90° twisted E-shaped resonators enables high-efficiency thermal modulation of linear polarization conversion. The asymmetric transmission of linearly polarized wave and circular dichroism simultaneously exhibit a pronounced switching effect dictated by temperature-controlled conductivity of VO2 inclusions. The proposed hybrid metamaterial design opens exciting possibilities to achieve dynamic modulation of terahertz waves and further develop tunable terahertz polarization devices.
Highlights
Y z x t materials Ge3Sb2Te632 and Ge2Sb2Te541
It is possible and worthwhile that the asymmetric transmission of linearly polarized wave and circular dichroism can be efficiently modulated by the phase transition effect of VO2, which provides an alternative route to realize switchable and functional THz devices
VO2 film layer can be deposited on the polyimide dielectric by the reactive magnetron sputtering technique[28], while VO2 islands and E-shaped metallic resonators can be fabricated by CF4/O2 plasma etching and the photolithography technique[28,30]
Summary
Y z x t materials Ge3Sb2Te632 and Ge2Sb2Te541. As one of the most important phase change materials, VO2 can exhibit an insulator-to-metal phase transition that can be electrically[27], thermally[28,29,30,31,42,43,44,45], or optically[46] tuned. It is possible and worthwhile that the asymmetric transmission of linearly polarized wave and circular dichroism can be efficiently modulated by the phase transition effect of VO2, which provides an alternative route to realize switchable and functional THz devices. Starting from the fundamental amplitude and phase, the polarization state of light can be tuned by controlling the time retardation with L-shaped microstructured surface[49]. They are not involved in the dynamic and flexible manipulation of the polarization state. The thermal switching of the asymmetric transmission and circular dichroism can be implemented Such dynamic control of phase transition metamaterials is of importance to acquire a variety of functionalities in the THz regime, such as filters, modulators and switches
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