2.576Tb/s (23×2×56Gb/s) mode division multiplexed 4PAM over 11.8 km differential mode delay uncompensated few-mode fiber using direct detection

2.576Tb/s (23×2×56Gb/s) mode division multiplexed transmission over 11.8km differential mode delay uncompensated few-mode fiber is experimentally demonstrated using direct-detection and 28GBaud 4-level pulse amplitude modulation (4PAM). Assuming 27.5% (training sequence, framing, and error correcting) overhead, the net bit-rate is 1.87Tb/s.