Real-Time Demonstration of 228.48 Pb/s·km Transmission Over 5 × 80-km 7-Core Fiber With 1.2-Tb/s/λ Transceivers Across 12-THz C + L Band

The exponential increase in global data traffic necessitates continued advances in optical fiber transmission capacity. Conventional single-mode fiber systems are rapidly approaching the fundamental nonlinear Shannon limit. Space-division multiplexing (SDM) has therefore emerged as a crucial pathway toward future ultra-high-capacity networks. Multi-core fiber (MCF) represents a particularly promising candidate due to its low inter-core crosstalk, compatibility with existing transceivers, and proven potential in experimental demonstrations. In this work, we report a real-time transmission experiment over a weakly-coupled 7-core MCF, for which the maximum inter-core crosstalk (XT) after 50 km transmission is less than −47.33 dB. Using commercial 155-GBaud transceivers with polarization-division-multiplexed 64-point quadrature-amplitude modulation (PDM-64QAM), a single-wavelength data rate of 1.2 Tb/s is realized across an extended C + L band (1524.3–1626.4 nm). Over 68 dense wavelength-division multiplexing (DWDM) channels, a total capacity of 571.2 Tb/s is transmitted with a distance of 404.58 km, achieving a capacity–distance product (CDP) of 228.48 Pb/s·km. It underscores the practicality and scalability of MCF-based SDM for the next-generation optical infrastructure.