5×85-Gb/s and 5×5.9-Gb/s Transmission over 360-km and 460-km Unrepeatered Fiber-Optic Links by Probabilistically Shaped Asymmetric QAM with Record Rate-Sensitivity Tradeoff
22 February 2018
We propose a novel probabilistically shaped asymmetric 4-QAM for high-loss channels such as unrepeatered fiber links or free-space communications. Over 360 km of pure silica core fiber, we achieve a 31% increase in information rate compared to QPSK, and are able to recover 5.9-Gb/s signals at 460 km (-7 dB SNR), where the recovery of QPSK fails completely
