  Enhanced-SSFM digital backpropagation (DBP) is experimentally demonstrated
and compared to conventional DBP. A 112 Gb/s PM-QPSK signal is transmitted over
a 3200 km dispersion-unmanaged link. The intradyne coherent receiver includes
single-step digital backpropagation based on the enhanced-SSFM algorithm. In
comparison, conventional DBP requires twenty steps to achieve the same
performance. An analysis of the computational complexity and structure of the
two algorithms reveals that the overall complexity and power consumption of DBP
are reduced by a factor of 16 with respect to a conventional implementation,
while the computation time is reduced by a factor of 20. As a result, the
proposed algorithm enables a practical and effective implementation of DBP in
real-time optical receivers, with only a moderate increase of the computational
complexity, power consumption, and latency with respect to a simple
feed-forward equalizer for dispersion compensation.
