Space-division multiplexed transmission over 3??3 coupled-core multicore fiber

We experimentally demonstrate transmission over a novel multicore fiber with 9 cores arranged in 3 groups of 3 cores, where strong coupling occurs within the groups and weak couplings between groups. We transmitted over 2500 km in a single group at a time and 715 km when all 9 cores are used. Low-loss 3D waveguides are used as couplers.