A Switchable Metalens Based on Active Tri-Layer Metasurface
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Metasurfaces, which are composed of two-dimensional arrays of subwavelength structures, can reshape the wavefront arbitrarily by introducing phase discontinuities with the entire 2π phase region. In this paper, we demonstrate a switchable metalens based on active tri-layer metasurfaces by hybridizing a phase-change material, vanadium dioxide (VO2). The reflection and transmission coefficients of the metasurface element and the focusing performance of the switchable metalens were studied and simulated. At room temperature (300 K), VO2 behaves as a semiconductor and our proposed metalens can reflect and converge the co-polarized terahertz wave with high efficiency, working as a reflective lens. When the temperature is up to around 400 K, the VO2 material is switched into metal phase and the proposed metalens is switched into its operating state as a transmission mode for the cross-polarized terahertz wave. By thermal stimulation or electrical bias, the switchable meta-devices proposed in this paper can be applied in the fields for imaging, communication, and power modulation.
KeywordsActive metasurface Vanadium dioxide Phase shift Switchable metalens
This paper is funded by the National Natural Science Foundation of China (No. 61205095), the Shanghai Young College Teacher Develop funding schemes (No. slg11006.)
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