Vittorio Curri, Full Professor, Department of Electronics and Telecommunications, Politecnico di Torino, Italy

Physical layer in optical networks is a set of transparent optical circuits – lightpaths – that has been extensively shown as reliably approximated  by additive white and Gaussian noise channels affected by the ASE noise from amplifiers and the nonlinear interference (NLI) from the Kerr effect. While coherent transceiver can be effectively modeled by the back-to-back characterization. We will first address the physics behind such approximation including also the statistical impairments due the PMD, PDL and filtering penalties, and other uncertainties. Then, we will show how the digital twin that integrate transmission impairment models of all network elements can be exploited to reliably evaluate QoT, latency and energy consumption on the topology. Finally, we will address the use of the digital twin as vendor neutral planning tool for disaggregated infrastructure and as on-line service  in the multi-layer hierarchical controller fully abstracting the physical layer for the optical device controller separated from the optical circuit development, so enabling multivendor networks with independent optical data transport and infrastructure control. We will also comments on th synergistic use of AI&ML techniques assisting the digital twin.