Bidirectional single-multicore-fiber spatial channel network based on a spatial cross-connect and multicore EDFA that efficiently accommodates asymmetric data traffic

In current wavelength division multiplexed (WDM) networks, capacity is deployed in a symmetrical manner, in which wavelength channels provide the same capacity in both directions. However, real data traffic in metro and backbone networks is observed to be considerably asymmetric resulting in wasted capacity in an under-loaded direction. This data traffic asymmetry is expected to increase further in the forthcoming Beyond 5G era due to newly emerging bandwidth-hungry services based on cloud computing. In such a situation, the wasted link capacity in the under-loaded direction can no longer be overlooked. In this paper, we propose a single-multicore-fiber (MCF) bidirectional spatial channel network (SCN) architecture that efficiently accommodates up and down asymmetric traffic. We present a proof-of-concept demonstration of the asymmetric bandwidth allocation in a single-MCF SCN by constructing a single-MCF bidirectional ring network testbed that comprises two spatial cross-connects based on 19-core fiber core selective switches with an ${\rm M} \times {\rm N}$ wavelength-selective switch and a bidirectional 7-core erbium-doped fiber amplifier with reversible optical isolators. Experimental results for bit error rate measurements of WDM optical signals traveling through different cores in different directions show there is almost no optical signal-to-noise ratio penalty for transmission through the single-MCF bidirectional ring network testbed.