标题： 基于电控超材料的色散拓扑转变主动控制 显示英文标题

标题： Actively controlling the topological transition of dispersion based on electrically controllable metamaterials

摘要： 拓扑过渡的等频率轮廓（IFC）从闭合的椭球体变为开放的双曲面，将为控制光的传播提供独特的能力。 然而，主动调节这些效应的能力仍然难以实现，相关的实验观察是非常期望的。 在这里，通过调节石墨烯层的化学势，研究了由石墨烯/电介质多层结构组成的可调电IFC。 特别地，我们展示了两种含有PEC/PMC杂质的各向异性零折射率介质中的主动控制传输。 最后，通过将可变电容二极管加入二维传输线系统，我们展示了基于电控超材料的主动控制磁拓扑过渡的实验演示。 随着电压的增加，我们测量了结构内部点源的不同辐射图案，并观察了IFC的相变过程。 主动调谐拓扑过渡的实现将为超材料的动力学控制开辟新的途径。 显示英文摘要

摘要： Topological transition of the iso-frequency contour (IFC) from a closed ellipsoid to an open hyperboloid, will provide unique capabilities for controlling the propagation of light. However, the ability to actively tune these effects remains elusive and the related experimental observations are highly desirable. Here, tunable electric IFC in periodic structure which is composed of graphene/dielectric multilayers is investigated by tuning the chemical potential of graphene layer. Specially, we present the actively controlled transportation in two kinds of anisotropic zero-index media containing PEC/PMC impurities. At last, by adding variable capacitance diodes into two-dimensional transmission-line system, we present the experimental demonstration of the actively controlled magnetic topological transition of dispersion based on electrically controllable metamaterials. With the increase of voltage, we measure the different emission patterns from a point source inside the structure and observe the phase-transition process of IFCs. The realization of actively tuned topological transition will opens up a new avenue in the dynamical control of metamaterials.