19.2 THz S+C+L Transmission over Field-Deployed Coupled-Core Multi-Core Fiber Enabled by Distributed Raman Amplification

We present the transmission of a 19.2 THz-wide signal spanning the S-, C-, and L-bands, over a standard-claddingdiameter, 69.3 km-long coupled-core four-core fiber (CC-4CF), field-deployed in the Italian city of L'Aquila. The transmission of 1540× 12.25 GBaud spatial super-channels with polarizationdivision multiplexed (PDM) 256-ary quadrature-amplitude modulation (256QAM), 64QAM, and 4QAM signals, relying on a hybrid amplification scheme integrating lumped amplification and distributed Raman amplification (DRA) with single-core pumping per direction, results in an aggregate throughput of 929.9 Tb/s estimated using generalized mutual information (GMI) and 864.8 Tb/s after forward-error correction (FEC) decoding. Uniformity of the DRA is verified by analyzing the system modedependent loss both with and without Raman amplification. Transmission of the same set of signals over a co-deployed 6.3 km-long CC-4CF, omitting Raman amplification, results in an aggregate throughput of 955 Tb/s estimated using GMI and 892.9 Tb/s after FEC-decoding, showing only a 3% improvement compared to the longer fiber link. This highlights the substantial benefit of using DRA to support multi-band wavelengthdivision multiplexing over coupled-core multi-core fibers (CCMCFs). This work reports the first demonstration of S+C+L band transmission over standard-cladding-diameter CC-MCFs, the first use of DRA in such fibers, and the highest reported throughput ever achieved over any field-deployed fiber.