100 km fiber span in 292 km, 2.38 Tb/s (16×160 Gb/s) WDM DQPSK polarization division multiplex transmission experiment without Raman amplification

We investigate the performance of 160 Gb/s WDM transmission with up to 100 km long fiber spans. Using differential quadrature phase-shift keying (DQPSK) and polarization division multiplexing (PolDM), a 160 Gb/s capacity per wavelength is realized at 40 Gsymbol/s rate. We demonstrate that in a relatively conventional EDFA-supported transmission line with an average span loss of 22 dB, a total distance of 292 km is reached with only three spans. Even without proper dispersion management and Raman amplification, we still observe clear eye openings for all channels. In this spectrally highly efficient system, we have achieved a bitrate × span distance product of 16 Tb/s km per wavelength which is, to our knowledge, the highest figure reported so far for 160 Gb/s WDM systems.