  A pragmatic coded modulation system is presented that incorporates signal
shaping and exploits the excellent performance and efficient high-speed
decoding architecture of staircase codes. Reliable communication within 0.62
bits/s/Hz of the estimated capacity (per polarization) of a system with L=2000
km is provided by the proposed system, with an error floor below 1E-20. Also,
it is shown that digital backpropagation increases the achievable spectral
efficiencies---relative to linear equalization---by 0.55 to 0.75 bits/s/Hz per
polarization.
