论文标题

通过辐射拓扑探测带拓扑的相变

Probing Phase Transition of Band Topology via Radiation Topology

论文作者

Ji, Chang-Yin, Lan, Wenze, Fu, Peng, Wang, Gang, Gu, Changzhi, Li, Jiafang, Yao, Yugui, Liu, Baoli

论文摘要

拓扑光子学引起了研究人员的广泛关注,因为它提供了全新的物理原理来操纵光线。光学材料的带拓扑使用Bloch状态定义的浆果相表征。到目前为止,拓扑物理学始终缺乏实验探测带拓扑的拓扑相变的标准。此外,可以通过辐射BLOCH状态的远场极化引起辐射拓扑,这用Stokes阶段描述。尽管这两种类型的拓扑都与乐队结构上的Bloch状态有关,但它们的发展几乎是独立的,这是令人惊讶的。在这里,我们揭示了辐射拓扑可以探测带的相变。从理论上讲,我们通过构造支持量子自旋效应的光学类似物的光子晶体来设计和实验表明这种有趣的现象。结果表明,当从微不足道变为非平底物时,远场极化涡流的拓扑电荷从+1变为-2或-2变为+1,这提供了一个新的标准,可以使用辐射拓扑探测频段拓扑的相变。我们的发现不仅提供了对带拓扑和辐射拓扑的有见地的理解,而且还可以作为操纵近距离光领域的新型途径。

Topological photonics has received extensive attention from researchers because it provides brand new physical principles to manipulate light. Band topology of optical materials is characterized using the Berry phase defined by Bloch states. Until now, the criteria for experimentally probing the topological phase transition of band topology has always been relatively lacking in topological physics. Moreover, radiation topology can be aroused by the far-field polarizations of the radiating Bloch states, which is described by the Stokes phase. Although such two types of topologies are both related to Bloch states on the band structure, it is rather surprising that their development is almost independent. Here, we reveal that the phase transition of band topology can be probed by the radiation topology. We theoretically design and experimentally demonstrate such an intriguing phenomenon by constructing photonic crystals that support optical analogs of quantum spin Hall effects. The results show that the topological charge of the far-field polarization vortex changes from +1 to -2 or from -2 to +1 when the band topology changes from trivial to non-trivial, which provides a new criterion to probe the phase transition of band topology using radiation topology. Our findings not only provide an insightful understanding of band topology and radiation topology, but also can serve as a novel route to manipulate the near and far fields of light.

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