Digital Twin Modelling of Cascaded Amplifiers in the COSMOS Testbed.

Digital twins provide a cost-effective means of evaluating performance, predicting network changes, and enhancing network administration and decision-making processes. However, acquiring detailed data for digital twin development remains a challenge due to commercial system constraints. City-scale testbeds, like COSMOS, offer practical solutions, aiding in data collection for modelling of digital twins. In this paper, we utilize data from experiments on the COSMOS testbed to design a digital twin model for the accumulation of gain ripple in cascaded Erbium-doped fiber amplifiers (EDFAs). We quantify the gain ripple in terms of its peak-to-valley ratios and identify optimal EDFA combinations. Moreover, we explore the impact of system parameters, and validate the proposed digital model through comparison with experimental results. We show that the differences between the digital twin predictions and experimental results are ≤ 0.1 dB.