Coherent Nyquist optical pulse transmission at nearly 1-Tb/s/λ over 1,600 km with a capacity of 21.5 Tb/s using PS-32 QAM signals.

We demonstrate the 1,600-km transmission at nearly 1-Tb/s/λ signals with a capacity of 21.5 Tb/s. Probabilistic shaping was newly applied to high-speed coherent optical Nyquist pulse transmission systems to maximize the transmission capacity. Employing a 160-GBd PS-32 QAM format, WDM signals at nearly 1-Tb/s/λ were successfully transmitted over 1,600 km with a capacity of 21.5 Tb/s.