Fig. 4
From: Quantum dash multi-wavelength lasers for Tbit/s coherent communications and 5G wireless networks
a A schematic of PAM-4 and QAM data format system. b Measured BER versus received power for PAM-4 B2B and after 25 km of SSMF transmission using a 1547.855 nm comb line of the 34.2 GHz QD MWL. The inset shows corresponding eye diagram for 25 km of SSMF transmission (chromatic dispersion of 17 ps/nm/km). c A constellation eye diagram obtained from filtered channel of 1552.92 nm for the 34.2 GHz QD MWL in the double polarization 16-QAM data format at 28 GBaud for B2B and 100 km SSMF transmission (chromatic dispersion of 17 ps/nm/km)