Electronic chips have reached a fundamental limit and efforts to maintain Moore's law trend are becoming increasingly challenging. Moreover, the advent of artificial intelligence with the widespread use of deep learning techniques have dramatically increased the need for fast and low-energy consumption processing units. It is then beyond any doubt that there is a concrete need for alternative schemes to do high-performance low-power signal processing. In this context, photonics has acquired a crucial role as optical devices are potentially much faster and efficient than electronic devices and could in principle lead to a sizable reduction in global energy consumption. The difficulty in designing all-optical integrated devices comes from the fact that nonlinear optical interactions are generally very weak limiting the possibility to control the photon flows at small scales. In this project, we plan to overcome this limitation by exploiting the strong nonlinear response of plasmonic systems at the nanoscale. In particular, we plan to use a cascaded second-order nonlinear process arising from the dynamic of free-electron inside the metal, as such nonlinearities could be much stronger than conventional crystalline lattice susceptibilities. As a result, we will generate ground-breaking new knowledge on light-matter interaction, and we could lay the foundations for low-power nonlinear optical interactions at the nanoscale. This could ultimately revolutionize a vast majority of data center and communication applications, providing a concrete route for a reduction of energy consumption. The top-tier experience and experimental resources of Prof. Junsuk Rho and the longstanding expertise in theory and simulation of Dr Cristian Ciracì are a perfect match for the positive outcome of the project.