The study of topological phases of light underpins a promising paradigm for engineering disorder-immune compact photonic devices with unusual properties. Combined with an optical gain, topological photonic structures provide a novel platform for micro- and nanoscale lasers, which could benefit from nontrivial band topology and spatially localized gap states. Here, we propose and demonstrate experimentally active nanophotonic topological cavities incorporating III–V semiconductor quantum wells as a gain medium in the structure. We observe room-temperature lasing with a narrow spectrum, high coherence, and threshold behaviour. The emitted beam hosts a singularity encoded by a triade cavity mode that resides in the bandgap of two interfaced valley-Hall periodic photonic lattices with opposite parity breaking. Our findings make a step towards topologically controlled ultrasmall light sources with nontrivial radiation characteristics.

光的拓扑相的研究为工程具有不寻常特性的无序免疫紧凑光子器件奠定了一个有前途的范例。与光学增益相结合，拓扑光子结构为微米级和纳米级激光器提供了一个新颖的平台，该平台可以受益于非平凡的带拓扑和空间局部间隙态。在这里，我们提出并演示了实验活性纳米光子拓扑腔，将 III-V 族半导体量子阱作为结构中的增益介质。我们观察到具有窄光谱、高相干性和阈值行为的室温激光。发射的光束具有由三重腔模式编码的奇点，该奇点位于两个具有相反奇偶性破缺的界面谷-霍尔周期性光子晶格的带隙中。我们的研究结果朝着具有非凡辐射特性的拓扑控制超小型光源迈出了一步。