12 b/s/Hz Spectral Efficiency Over the C-band Based on Comb-Based Superchannels

We present transmission of three 50 × 24 Gbaud PM-256QAM superchannels with an overall spectral efficiency of 12 b/s/Hz over the entire C-band. Each comb-based superchannel combines a single shared optical pilot tone with a low-overhead pilot-based DSP. The pilot tone is used to lock the transmitter and the receiver comb seed lasers, suppressing carrier offsets. Combined with optimized insertion ratio of the digital pilot symbols, the total overhead is minimized, avoiding any excess loss in spectral efficiency. Our results demonstrate the feasibility to exploit the unique properties of frequency combs in the design of high spectral efficiency multi-Tb/s superchannels.