20-Gb/s Single-Feeder WDM-PON Using Partial-Response Maximum Likelihood Equalizer

Wavelength-division-multiplexed passive optical network (WDM-PON) has been recognized as a future proof access solution. Reflective semiconductor optical amplifier (RSOA) is often employed for colorless operation of the optical network unit (ONU). However, the small electrical bandwidth of RSOA limits the speed of uplink. Moreover, chromatic dispersion together with high chirp of the directly modulated signal limits the upstream transmission distance. In addition, in-band crosstalk arising from reflections further limits the performance of a single fiber loop-back system. In this letter, characteristics of high-capacity RSOA-based WDM-PON in bidirectional architecture are experimentally studied. To overcome the constraints on uplink, we propose a novel receiver based on a partial-response maximum likelihood (PRML) equalizer. The 20-Gb/s operation of 1-GHz RSOA is demonstrated for a bidirectional distance up to 20 km. Furthermore, the proposed PRML equalizer is compared with other equalizers in various experiments to demonstrate its superior performance.