Optical networks, for 400G and beyond, require flexibility and agility from network elements, especially from coherent transceivers. Higher baud rates are made possible using new electrooptic technologies. Multi-dimensional modulation formats provide improved tolerance to noise and fiber nonlinearities. Constellation shaping further improves these tolerances while allowing a finer granularity in selection of capacity. Frequency division multiplexing also provides improved tolerance to the nonlinear characteristics of fiber. Algorithms with reduced computation complexity allow the implementation at-speed of direct precompensation of nonlinear propagation effects. FlexEthernet and FlexOTN allow network operators to optimize capacity on their optical transport networks.
Kim Roberts, Kim Roberts,
"Flexible optical transceivers", Proc. SPIE 10561, Next-Generation Optical Communication: Components, Sub-Systems, and Systems VII, 1056104 (29 January 2018); doi: 10.1117/12.2295350; https://doi.org/10.1117/12.2295350