Achieving high budget classes in the downstream link of 50G-PON

With 50G passive optical networks (PONs) currently being standardized, we review the challenges of meeting the high loss budgets required in such high speed fiber access networks. Simulations of the 50 Gb/s link performance show the impact of critical parameters when using 25G-class avalanche photodiode receivers with digital signal processing. We describe how a 1342 nm electro-absorption modulated laser, with an external semiconductor optical amplifier, enables an E2-class, 20 km, downstream link for ITU-T, 50G-PON to be demonstrated. Using a 25G-class receiver and real-time equalization, a link budget of 35.6 dB was measured. With more powerful equalization performed offline, an increase in the link budget to 38.2 dB is also demonstrated.