High capacity submarine transmission systems

· Coherent technology unlocked capacity of undersea systems · Increased several times the capacity of the legacy systems· Brought to life new generation of dispersion uncompensated systems with capacities more than 10 Tb/s per fiber · Laboratory experiments are close to Shannon limit · Further increase in capacity can be achieved · Better bandwidth utilization: spectral shaping and variable spectral efficiency · Expansion of the bandwidth into L band · Is SDM the next step? · Power efficiency is an attractive argument.