The recently established paradigm of higher-order topological states of matter has shown that not only edge and surface states^1,2 but also states localized to corners, can have robust and exotic properties^{3,4,5,6,7,8,9}. Here we report on the experimental realization of novel corner states made out of visible light in three-dimensional photonic structures inscribed in glass samples using femtosecond laser technology^10,11. By creating and analysing waveguide arrays, which form two-dimensional breathing kagome lattices in various sample geometries, we establish this as a platform for corner states exhibiting a remarkable degree of flexibility and control. In each sample geometry we measure eigenmodes that are localized at the corners in a finite frequency range, in complete analogy with a theoretical model of the breathing kagome^{7,8,9,12,13,14}. Here, measurements reveal that light can be ‘fractionalized,’ corresponding to simultaneous localization to each corner of a triangular sample, even in the presence of defects.

最近建立的物质高阶拓扑状态的范例表明，不仅边缘和表面状态^1,2，而且局部化到角的状态，都可以具有鲁棒且奇特的属性^{3,4,5,6,7,8,9}。在这里，我们报告使用飞秒激光技术在玻璃样品中刻印的三维光子结构中由可见光制成的新颖角状态的实验实现^10,11。通过创建和分析在各种样品几何形状中形成二维呼吸kagome晶格的波导阵列，我们将其建立为角状态的平台，展现出显着的灵活性和可控制性。在每个样本几何中，我们都测量本征模，该本征模位于有限的频率范围内的拐角处，与呼吸^{假名7,8,9,12,13,14}的理论模型完全相似。在这里，测量结果表明，即使存在缺陷，光也可以被“分散”，对应于同时定位到三角形样品的每个角。