Makwana Mehul P, Chaplain Gregory
Department of Mathematics, Imperial College London, London, SW7 2AZ, UK.
Multiwave Technologies AG, 3 Chemin du Prê Fleuri, 1228, Geneva, Switzerland.
Sci Rep. 2019 Dec 12;9(1):18939. doi: 10.1038/s41598-019-55485-0.
Strategically combining four structured domains creates the first ever three-way topological energy-splitter; remarkably, this is only possible using a square, or rectangular, lattice, and not the graphene-like structures more commonly used in valleytronics. To achieve this effect, the two mirror symmetries, present within all fully-symmetric square structures, are broken; this leads to two nondistinct interfaces upon which valley-Hall states reside. These interfaces are related to each other via the time-reversal operator and it is this subtlety that allows us to ignite the third outgoing lead. The geometrical construction of our structured medium allows for the three-way splitter to be adiabatically converted into a wave steerer around sharp bends. Due to the tunability of the energies directionality by geometry, our results have far-reaching implications for applications such as beam-splitters, switches and filters across wave physics.
通过策略性地组合四个结构化域，创造出了首个三向拓扑能量分离器；值得注意的是，这只有使用正方形或矩形晶格才有可能实现，而不是谷电子学中更常用的类石墨烯结构。为了实现这种效果，所有完全对称的正方形结构中存在的两个镜面对称性被打破；这导致了两个非不同的界面，谷霍尔态就驻留在这些界面上。这些界面通过时间反演算符相互关联，正是这种微妙之处使我们能够激发第三条出射引线。我们结构化介质的几何结构允许三向分离器在急转弯处绝热地转换为波操纵器。由于能量方向性可通过几何结构进行调节，我们的结果对诸如波物理学中的分束器、开关和滤波器等应用具有深远影响。
