Fibre and bulk optical isolators are widely used to stabilize laser cavities by preventing unwanted feedback. However, their integrated counterparts have been slow to be adopted. Although several strategies for on-chip optical isolation have been realized, these rely on either integration of magneto-optic materials or high-frequency modulation with acousto-optic or electro-optic modulators. Here we demonstrate an integrated approach for passively isolating a continuous-wave laser using the intrinsically non-reciprocal Kerr nonlinearity in ring resonators. Using silicon nitride as a model platform, we achieve single ring isolation of 17–23 dB with 1.8–5.5-dB insertion loss, and a cascaded ring isolation of 35 dB with 5-dB insertion loss. Employing these devices, we demonstrate hybrid integration and isolation with a semiconductor laser chip.

光纤和体光隔离器被广泛用于通过防止不需要的反馈来稳定激光腔。然而，他们的综合同行被采纳的速度很慢。尽管已经实现了多种片上光隔离策略，但这些策略要么依赖于磁光材料的集成，要么依赖于使用声光或电光调制器的高频调制。在这里，我们展示了一种使用环形谐振器中固有的非互易克尔非线性被动隔离连续波激光器的集成方法。使用氮化硅作为模型平台，我们实现了 17-23 dB 的单环隔离度和 1.8-5.5-dB 的插入损耗，以及 35 dB 的级联环隔离度和 5-dB 的插入损耗。使用这些设备，我们展示了半导体激光芯片的混合集成和隔离。