Implications of Distributed Link Polarization-Dependent Loss on Bitwise Achievable Information Rates for Probabilistically Shaped and Uniform DP 64-QAM

The statistical behaviors of bitwise achievable information rates (BW AIRs) and effective signal-to-noise ratios (SNRs) due to polarization-dependent loss (PDL) are experimentally characterized for probabilistically shaped and uniform dualpolarization 64-ary quadrature amplitude modulation with a bit rate of 250 Gb/s. A single-span recirculating loop is used to emulate distributed link PDL. Histograms for the BW AIR and effective SNR following offline signal processing resemble shifted, mirrorimage Maxwell probability density functions for both constellations and two different per-loop PDL values. For a transmission distance of 1200 km and a per-loop PDL of 1.3 dB, the outage probabilities for the shaped and uniform constellations are estimated tobe 1.1 × 10^-3 and 4.4 × 10^-1, respectively. Moreover, for an outage probability ≤ 4.0 × 10^-3, the increase in transmission distance due to shaping is reduced by 50% compared to that for PDL free transmission.