ABSTRACT
For effective wavefront management in the optical infrared range, dynamic all-dielectric metasurfaces, always based on phase transition materials, particularly G e 2 S b 2 T e 5 (GST), can be used. In this paper, we propose a GST-based tunable metasurface by structuring the phase-change material GST. We confirm that the nanopillar we designed has high transmittance in the wavelength band around 1550 nm and can fully cover the 0â¼2π phase. Based on these characteristics, we can achieve beam steering and a focusing effect in amorphous phase by elaborately arranging GST nanopillars, while the aforementioned optical phenomena disappear in crystalline phase. Additionally, by arranging the array of vortex phases, we also realize switching the perfect composite vortex beam (PCVB) when changing the crystal state of GST, and simulate the generation of PCVB with different topological charges and sizes in amorphous phase. We believe that our research results can serve as a reference for multifunctional optical surfaces, dynamic optical control, optical communication, and information processing.
ABSTRACT
In this paper, we demonstrate an adjustable trifunctional absorber that can achieve the conversion of broadband, narrowband and superimposed absorption based on the phase transition material vanadium dioxide (VO2) in the mid-infrared domain. The absorber can achieve the switching of multiple absorption modes by modulating the temperature to regulate the conductivity of VO2. When the VO2 film is adjusted to the metallic state, the absorber serves as a bidirectional perfect absorber with switching capability of wideband and narrowband absorption. The superposed absorptance can be generated while the VO2 layer is converted to the insulating state. Then, we introduced the impedance matching principle to explain the inner mechanism of the absorber. Our designed metamaterial system with a phase transition material is promising for sensing, radiation thermometer and switching devices.
