128 Gbit/s × 80 Ch signal transmission over 1840 Km of standard G652.D fiber

We report successful demonstration of signal transmission of 80×128 Gbit/s coherent PDM-QPSK wavelength-division-multiplexing (WDM) channels spaced at 50 GHz over 23 spans of 80 km standard Sterlite OH-LITE G652.D fiber. The loss of each span was compensated with a variable gain erbium-doped fiber amplifier (EDFA). A dynamic gain equalizer was used after every 6 spans to compensate gain ripple of the EDFAs. No dispersion compensation was used in the link. For BER measurements, a commercial 127.156 Gbit/s real-time coherent PDM-QPSK transponder with a 20% overhead soft-decision forward-error correction (SD-FEC), yielding a spectral efficiency of 2.03 bit/s/Hz was used. The bit-error ratio (BER) of all channels across C-band was measured to be better than the pre-SD-FEC limit of 2.0×10² after 1840 km transmission using a launch power of 0 dBm/ch.