High-spectral-efficiency transmission of PDM 256-QAM with Parallel Probabilistic Shaping at Record Rate-Reach Trade-offs

We demonstrate the transmission of near-optimal low-complexity probabilistically shaped PDM 256-QAM over multiple low-loss all-Raman amplified 50-km large effective area fiber spans, with spectral efficiencies from 14.1 b/s/Hz to 8.9 b/s/Hz at reaches from 500 km to 4000 km.