Tolerance to nonlinearity of 40 Gb/s BPSK-based coherent solution over legacy systems based on non-zero dispersion-shifted fibers

We experimentally assess the performance of coherent PDM-BPSK at 40Gb/s over non-zero dispersion-shifted fiber. The BPSK-based solution is found about 7.5dB more robust than the QPSK-based solution against cross-nonlinearities induced by 10Gb/s neighbor channels.