Transmission Performance of 448 Gb/s Single-Carrier and 1.2 Tb/s Three-Carrier Superchannel Using Dual-Polarization 16-QAM With Fixed LUT Based MAP Detection

Abstract

Transmission of single-carrier 448 Gb/s dual-polarization 16-ary quadrature-amplitude-modulation (DP 16-QAM) electrical time-division multiplexed (ETDM) signal and a 1.206 Tb/s three-carrier superchannel ETDM signal using DP 16-QAM is demonstrated by applying a fixed look-up table (LUT) based on maximum-a-posteriori (MAP) detection. The MAP detector is used to mitigate the effect of pattern dependent distortion in the transmitted signal arising from the high symbol rates. Different decision rules for the MAP detector are considered based on multiple observations of the same symbol as the detection window advances through the received symbol sequence. The back-to-back optical signal-to-noise ratios for a bit error ratio of $\mathbf {10^{-3}}$ are 26.9 and 26.4 dB for the 448 Gb/s signal (12% overhead with 7% for forward error correction (FEC) coding overhead) and 1.206 Tb/s superchannel signal (20% overhead with 15% for FEC coding overhead), respectively. Compared to conventional MAP detection, a seven-symbol minimum distance MAP detector reduces the required OSNR by about 0.8 and 1 dB at the FEC thresholds of $\mathbf {3.8\times 10^{-3}}$ and $\mathbf {1.9\times 10^{-2}}$ for the 448 Gb/s signal and 1.206 Tb/s superchannel signal, respectively. Transmission over 1200 and 1500 km of standard single-mode fiber with EDFA amplification is achieved for the 448 Gb/s signal and 1.206 Tb/s superchannel signal, respectively.