O-Band $8\times100$ G Data Transmission With 240 GHz Channel Spacing

In this letter, we show an approach to 800G Ethernet based on dense channel allocation in the O-band and successfully demonstrate $8\times 54$ GBaud PAM-4 with narrowest so far 240 GHz channel grid data transmission below HD-FEC over 1 km of standard single mode fiber (SSMF) without any optical amplification, resulting in a total net throughput of 800 Gbit/s. Additionally we study theoretical limits of FWM on 108 Gbit/s channel system in SSMF zero-dispersion region.