High-capacity optical communication relayed by multi-core amplifier on deployed submarine seven-core fiber cable

Space division multiplexing (SDM), particularly multi-core fiber (MCF) technology, represents a promising solution for high-density cabling in duct-constrained scenarios such as submarine cable systems. Although recent laboratory experiments and prototype trials have demonstrated the feasibility of MCF-based submarine cables, a complete optical communication validation of a real-world MCF submarine cable link incorporating optical amplifiers has remained a critical necessity. Here, we demonstrate a field validation of the MCF submarine cable communication with an end-to-end system. Based on a field-deployed 7-core fiber submarine cable infrastructure, we achieved a record-breaking net transmission rate of 410.5 Tbit·s^-1 over a 140 km 7-core fiber cable link by employing the matched C + L Band cladding-pumped 7-core MC-EDFA. The measurements indicate slight variation in attenuation and crosstalk compared to the pre-cabling conditions, confirming the MCF's robustness to deployment and submarine disturbances. Furthermore, the developed 7-core MC-EDFAs maintain gains above ~18 dB and ~21 dB over the full C and L Bands, respectively, at an input power of -5 dBm, effectively compensating for span losses of submarine fiber cable. This successful field demonstration marks a crucial step towards the commercial implementation of integrated MC-EDFA SDM submarine optical communication systems for practical high-capacity applications.