Experimental verification of EGN model in 11-THz C+L broadband 400G real-time transmission with digital sub-carrier multiplexing

Abstract

To support high-quality network plan, reliable operation and efficient service provisioning, the quality of transmission estimation (QoT-E) tool, which predicts the penalty of transmission impairments, is highly required. Among these channel impairments, non-linear-interference noise (NLIN) in high-speed, large-capacity and long-reach transmission systems with advanced modulation formats and powerful digital signal processing (DSP) algorithms is complex and difficult to be accurately estimated, thus an precise and practical model of NLIN is desperately desired as one of the key components for QoT-E. Nowadays, 400Gb/s/ch combined with multi-band transmission has become a research hotspot achieving larger capacity without deploying new fibers. However, in this multi-band scenario, the interaction of NLIN with the stimulated Raman scattering (SRS) must be properly considered. In this paper, an equivalent attenuation coefficient assisted enhanced Gaussian noise (EGN) model which considers the impact of SRS on the nonlinear interference in C+L band, is proposed and experimentally verified. The real-time experiments of 400Gb/s/ch transmission system in 11-THz C+L band over 14x75 km G.652 and 14x100 km G.654E fiber links are carried out using coherent transponders modulated with 91.6 GBaud digital sub-carrier multiplexing (DSCM) based probabilistic constellation shaping (PCS) 16QAM format, achieving a net spectral efficiency of 4 bit/s/Hz. The experimental results show that the maximum deviation of NLI induced OSNR penalty at different frequencies across the whole C+L band is found to be less than 0.22 dB. This work could potentially provide an effective and accurate tool for QoT-E estimation in broadband C+L or even multiband systems, paving the way for intelligent management and control of high-capacity and flexible optical networks.