Yoshimi Hironobu, Yamaguchi Takuto, Katsumi Ryota, Ota Yasutomo, Arakawa Yasuhiko, Iwamoto Satoshi
Opt Express. 2021 Apr 26;29(9):13441-13450. doi: 10.1364/OE.422962.
We experimentally demonstrate topological slow light waveguides in valley photonic crystals (VPhCs). We employed a bearded interface formed between two topologically-distinct VPhCs patterned in an air-bridged silicon slab. The interface supports both topological and non-topological slow light modes below the light line. By means of optical microscopy, we observed light propagation in the topological mode in the slow light regime with a group index over 30. Furthermore, we confirmed light transmission via the slow light mode even under the presence of sharp waveguide bends. In comparison between the topological and non-topological modes, we found that the topological mode exhibits much more efficient waveguiding than the trivial one, demonstrating topological protection in the slow light regime. This work paves the way for exploring topological slow-light devices compatible with existing photonics technologies.
我们通过实验证明了谷光子晶体（VPhC）中的拓扑慢光波导。我们采用了在空气桥接硅平板中图案化的两个拓扑不同的VPhC之间形成的锯齿状界面。该界面在光线以下支持拓扑和非拓扑慢光模式。通过光学显微镜，我们观察到在慢光区域中拓扑模式下的光传播，其群折射率超过30。此外，我们证实即使在存在尖锐波导弯曲的情况下，光也能通过慢光模式传输。在拓扑模式和非拓扑模式的比较中，我们发现拓扑模式比平凡模式表现出更高效的波导，证明了在慢光区域中的拓扑保护。这项工作为探索与现有光子技术兼容的拓扑慢光器件铺平了道路。
