Transoceanic-Class WDM/SDM Transmission of PDM-QPSK Signals Over 12-Coupled-Core Fiber

We demonstrated a transoceanic-class long-haul transmission over 12-coupled-core fiber (12-CCF) with a standard cladding diameter of 125 $\mu$m. Nine-channel wavelength-division multiplexed (WDM) and 12-core spatial-division multiplexed 32-Gbaud polarization-division multiplexed quadrature phase shift keying signals were transmitted over a recirculating loop composed of a single 52-km span of the 12-CCF. Error-free transmission after forward error correction was achieved up to 9360 km in the WDM configuration centered at 1536.6, 1550.9, and 1560.6 nm. The estimated temporal spread due to SMD and root-mean-square (rms) MDL per 52-km span was 0.090 ns and 0.26 dB, respectively, and their wavelength dependence in the C-band was small. Using a numerical Monte Carlo simulation, we also evaluated transmission capacity over coupled-core multi-core fibers under SMD and MDL. We confirmed that a 12-CCF with the rms MDL of less than 0.5 dB per 50-km span has the potential for an ultra-long-haul transmission over 10 000 km.