Field Trial of a 1 Tbit/s Super-Channel Network Using Probabilistically Shaped Constellations

We successfully tested the suitability of probabilistically shaped constellations in a German nationwide fibre ring of the R&D field test network of Deutsche Telekom. In this ring eight German cities can be reached by add/drop nodes implemented by passive optical add/drop multiplexers, offering 12 bands of 400 GHz widths at the extended C-band. Multiple cascaded add/drop multiplexer are reducing the available bandwidth and we respectively applied of 150 GHz and 200 GHz, to transmit a 1 Tbit/s 4-carriers super-channel with an extended family of probabilistically shaped constellations using 16QAM, 36QAM and 64QAM. We verified in the field environment by two examples, that probabilistically shaping is outperforming standard 64QAM formats in reach. We experimentally tested two typical 1 Tb/s working paths with 420km and 920km demonstrating spectral efficiencies of 6.75 and 5 bit/s/Hz. The reach of about 1500km was extrapolated for a 1 Tb/s super-channel in a 200 GHz bandwidth. For longer distances the bitrates have to be reduced and for the longest bi-directional path of the test network, i.e. a protection path of 2,160 km, the maximum bitrate was 800 Gb/s