First Real-Time 221.9 Pb/S∙Km Transmission Capability Demonstration Using Commercial 138-Gbaud 400 Gb/S Backbone OTN System over Field-Deployed Seven-Core Fiber Cable with Multiple Fusion Splicing

The core-division-multiplexed (CDM) transmission technique utilizing uncoupled multi-core fiber (MCF) is considered a promising candidate for next-generation long-haul optical transport networks (OTNs) due to its high-capacity potential. For the field implementation of MCF, it is of great significance to explore its long-haul transmission capability using high-speed OTN transceivers over deployed MCF cable. In this paper, we investigate the real-time long-haul transmission capability of a deployed seven-core MCF cable using commercial 138-Gbaud 400 Gb/s backbone OTN transceivers with a dual-polarization quadrature phase shift keying (DP-QPSK) modulation format. Thanks to the highly noise-tolerant DP-QPSK modulation format enabled by the high baud rate, a real-time 256 Tb/s transmission over a 990.64 km (14 × 70.76 km) deployed seven-core fiber cable with more than 600 fusion splices is field demonstrated for the first time, which achieves a real-time capacity–distance product of 221.9 Pb/s∙km. Specifically, the long-haul CDM transmission is simulated by cascading the fiber cores of two segments of 70.76 km seven-core fibers. And dynamic gain equalizers (DGEs) are utilized to mitigate the impacts of stimulated Raman scattering (SRS) and the uneven gain spectra of amplifiers in broadband transmissions by equalizing the power of signals with different wavelengths. This field trial demonstrates the feasibility of applying uncoupled MCF in long-haul OTN transmission systems and will contribute to its field implementation in terrestrial fiber cable systems.