Transmission of 300 GBd QAM Signals Over Trans-Oceanic Distances Using Optical Arbitrary Waveform Generation and Measurement (OAWG/OAWM)

To sustain the persistent traffic growth in optical networks, symbol rates are continuously increasing, in particular in long-haul and submarine systems, where efficient exploitation of the installed fiber infrastructure is key. However, while commercial long-haul transceivers already offer symbol rates of 200 GBd, exploring the potential of transmission at symbol rates beyond this landmark still represents a challenge. One of the main difficulties is to reliably generate and analyze high-quality quadrature amplitude modulation (QAM) signals at bandwidths of more than 200 GHz, exceeding the capabilities of available test and measurement instrumentation. In this paper, we demonstrate the potential of high-symbol-rate transmission at 300 GBd over trans-oceanic distances, exploiting the concepts of optical arbitrary waveform generation (OAWG) and optical arbitrary waveform measurement (OAWM) for synthesizing and analyzing the associated data signals. Using dual-polarization probabilistic-constellation-shaped (PCS) 36QAM signals, we achieve net bit rates of 2.45 Tbit/s over 1 815 km. For PCS-16QAM signals, the transmission distance is extended to 9 680 km while supporting a net bit rate of 1.63 Tbit/s. In the back-to-back setup, the net bit rate is increased to 2.88 Tbit/s using 64QAM signals. To the best of our knowledge, our experiments achieve the highest symbol rate so far transmitted over a distance exceeding 100 km. Furthermore, the demonstrated distances for target net bit rates of 1.6 Tbit/s and 2.4 Tbit/s surpass previous demonstrations by more than an order of magnitude.