Multimode nonlinear devices have attracted considerable attention during the last 5 years. Nonlinear interactions among different modes have unlocked the development of a number of devices and functionalities that are typically hard to realize by using single mode devices (e.g. broadband frequency generation, mode switching, all optical modulation and etc). This focus session is devoted to the discussion of multimode nonlinear components. In detail, contributions are expected for the following topics (but not limited to): - Intermodal nonlinear interactions in optical fibre and integrated devices - Multimode components for all optical integrated processors - Multimodal coupling devices in silicon photonic and related technologies.