Generation and Transmission of 100-Gb/s PDM 4-PAM Using Directly Modulated VCSELs and Coherent Detection

We generate a 100-Gb/s line rate signal by directly modulating a 1.5 µm VCSEL with a 25-Gbaud 4-level signal and polarization multiplexing. By using digital coherent detection, we successfully transmit the signal over 160-km standard single-mode-fiber (SSMF) with 20% hard-decision forward-error-correction