Net 1-Tb/s/lambda PS-256-QAM coherent transmission with a 3-MHz DFB laser enabled by residual carrier modulation

We propose a residual-carrier modulation scheme for carrier frequency and phase recovery. With a low-cost 3-MHz linewidth DFB laser, we demonstrate a net rate of 1-Tb/s PS-256-QAM transmission over 80-km SSMF. The proposed scheme offers up to 2.77 bit/4D-symbol GMI improvement compared with time-domain pilots.