Investigation of low code rate DP-8PSK as an alternative to DP-QPSK

Low code rate DP-8PSK was studied as an alternative to DP-QPSK for long distance coherent communications. For 4,000 km transmission with multiple link configurations, low code rate DP-8PSK is shown to have 1.6 ! 1.8 dB span loss budget over DP-QPSK for the same spectral efficiency through simulations.