Digital coherent communication and advanced coding technologies for ultra-long-haul optical transmissions

Digital coherent communication technologies have shown superior performance in supporting high-bit-rate optical communications, including very high fiber chromatic dispersion (CD) and polarization mode dispersion (PMD) tolerance, and high spectral efficiency. In this paper, we will review the typical system design and the operation principles of dual-polarization digital coherent optical communications, and further investigate the transmission of 100Gb/s optical signals over transoceanic distances. We introduce LDPC based advanced coding schemes to support digital coherent communication systems for extra system margin from the FEC coding perspective.