Uemura Takahiro, Moritake Yuto, Yoda Taiki, Chiba Hisashi, Tanaka Yusuke, Ono Masaaki, Kuramochi Eiichi, Notomi Masaya
Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, 152-8550, Tokyo, Japan.
NTT Basic Research Laboratories, Nippon Telegraph and Telephone Corporation, 3-1 Morinosato-Wakamiya, Atsugi, 243-0198, Kanagawa, Japan.
Sci Adv. 2024 Aug 23;10(34):eadp7779. doi: 10.1126/sciadv.adp7779.
Photonic topological insulators (PTIs) have been proposed as an analogy to topological insulators in electronic systems. In particular, two-dimensional PTIs have gained attention for the integrated circuit applications. However, controlling the topological phase after fabrication is difficult because the photonic topology requires the built-in specific structures. This study experimentally demonstrates the band inversion in two-dimensional PTI induced by the phase transition of deliberately designed nanopatterns of a phase change material, GeSbTe (GST), which indicates the first observation of the photonic topological phase transition in two-dimensional PTI with changes in the Chern number. This approach allows us to directly alter the topological invariants, which is achieved by symmetry-breaking perturbation through GST nanopatterns with different symmetry from original PTI. The success of our scheme is attributed to the ultrafine lithographic alignment technologies of GST nanopatterns. These results demonstrate how to control photonic topological properties in a reconfigurable manner, providing insight into the possibilities for reconfigurable photonic processing circuits.
光子拓扑绝缘体（PTIs）已被提出作为电子系统中拓扑绝缘体的类比。特别是二维PTIs在集成电路应用中受到了关注。然而，制造后控制拓扑相很困难，因为光子拓扑需要内置特定结构。本研究通过实验证明了由相变材料GeSbTe（GST）的故意设计的纳米图案的相变引起的二维PTI中的能带反转，这表明首次观察到二维PTI中随着陈数变化的光子拓扑相变。这种方法使我们能够直接改变拓扑不变量，这是通过具有与原始PTI不同对称性的GST纳米图案的对称破缺微扰来实现的。我们方案的成功归功于GST纳米图案的超精细光刻对准技术。这些结果展示了如何以可重构的方式控制光子拓扑特性，为可重构光子处理电路的可能性提供了见解。
