Demonstration of the First Real-Time End-to-End 40-Gb/s PAM-4 for Next-Generation Access Applications Using 10-Gb/s Transmitter

We demonstrate the first known experiment of a real-time end-to-end 40-Gb/s pulse amplitude modulation (PAM)-4 system for next-generation access applications using 10-Gb/s class transmitters only. Based on the measurement of a real-time 40-Gb/s PAM system, low-cost upstream and downstream link power budgets are estimated. Up to 27 and 25 dB power budgets for 10- and 20-km standard single-mode fiber upstream links using erbium-doped fiber amplifiers (EDFA) preamplifiers are achieved. For downstream links using booster EDFAs and avalanche photodiode receivers, power budgets of 26.5 and 24.5 dB are feasible for 10- and 20-km SMFs, respectively. In addition, we show that colorless 40-Gb/s PAM-4 transmission over 20-km SMF in the C-band is achievable.