All-optical metro-access integration network bidirectional transmission enabled by coherent digital subcarrier multiplexing

The ever-increasing demand for improved speeds, expanded bandwidth, and reduced latency in emerging applications has not only driven the recent advanced algorithm breakthroughs but also fostered closer integration of metro and access networks. This work proposes a novel all-optical metro-access integration network (MAIN) enabled by coherent digital subcarrier multiplexing technology. This specially designed architecture can effectively eliminate the latency and jitters caused by the optical–electrical–optical conversion in the conventional scheme and save wavelength resources at the same time. For experimental validation, we successfully demonstrate 400G bidirectional coherent transmission within our proposed architecture, involving three nodes in the metro network and the access network as an example. Also, the related problems during the transmission are extensively discussed with the experimental results. Finally, we reach an aggregation rate of ${4} \times {100}\;{\rm Gbps}$ using a DP-16QAM signal. By integrating a SOA into the transmitter of the ONU, a power budget of 32.6 dB with a 29 dB dynamic range is achieved. In addition, the experimental results also show that the proposed all-optical MAIN architecture can be smoothly combined with the TFDM scheme to further enhance the flexibility, which also paves the way for further research on the next-generation coherent metro and access network.