Flexible Transmission Enabled by Novel M2-QAM Formats with Record Distance - Spectral Efficiency Tuneability

We propose a variable M
²
-QAM format and coding scheme and demonstrate record distance - spectral efficiency tuneability by 6.4 bit/s/Hz and ΔL≈18x, respectively, at 400 and 600 Gb/s per carrier and report record terrestrial reach for high spectral efficient up to 256QAM.