Malomed Boris A
Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, and Center for Light-Matter Interaction, Tel Aviv University, Tel Aviv, Israel.
Light Sci Appl. 2025 Jan 3;14(1):29. doi: 10.1038/s41377-024-01709-6.
This item from the News and Views (N&V) category aims to provide a summary of theoretical and experimental results recently published in ref. , which demonstrates the creation of corner modes in nonlinear optical waveguides of the higher-order topological insulator (HOTI) type. Actually, these are second-order HOTIs, in which the transverse dimension of the topologically protected edge modes is smaller than the bulk dimension (it is 2, in the case of optical waveguide) by 2, implying zero dimension of the protected modes, which are actually realized as corner or defect ones. Work reports the prediction and creation of various forms of the corner modes in a HOTI with a fractal transverse structure, represented by the Sierpiński gasket (SG). The self-focusing nonlinearity of the waveguide's material transforms the corner modes into corner solitons, almost all of which are stable. The solitons may be attached to external or internal corners created by the underlying SG. This N&V item offers an overview of these new findings reported in ref. and other recent works, and a brief discussion of directions for further work on this topic.
这篇来自“新闻与观点”（N&V）类别的文章旨在总结近期发表在参考文献中的理论和实验结果，该文献展示了在高阶拓扑绝缘体（HOTI）型非线性光波导中角模式的产生。实际上，这些是二阶HOTI，其中拓扑保护边缘模式的横向尺寸比体尺寸（在光波导的情况下为2）小2，这意味着受保护模式的维度为零，实际上它们表现为角模式或缺陷模式。该工作报道了在具有分形横向结构的HOTI（以谢尔宾斯基垫片（SG）为代表）中各种形式角模式的预测和产生。波导材料的自聚焦非线性将角模式转变为角孤子，几乎所有角孤子都是稳定的。这些孤子可以附着在由底层SG产生的外部或内部角上。这篇N&V文章概述了参考文献及其他近期工作中报道的这些新发现，并简要讨论了该主题进一步研究的方向。
