Minimizing ONU Complexity by Offloading Optical Receiver Pre-Amplification to the Passive Fiber Plant

The continuous growth in fixed-access bandwidth delivered over passive optical networks (PON) has reached a point at which optical network units (ONU) face a shortage of highly sensitive broadband photoreceivers. An active optical access network could be beneficial as it reduces the sensitivity requirements for downstream reception. Yet, this strategy gives up an originally passive outside fiber plant as it requires to place a local electrical supply within the optical distribution network. To mitigate this architectural burden, a novel concept for an optical extender box based on an optically fed semiconductor optical amplifier (SOA) is proposed and experimentally investigated. An optical budget of 32 dB can be supported for an access network with a 1:64 split. No significant penalty is incurred with respect to traditional PONs or the use of extender boxes based on Erbium-doped fiber as active gain medium. The performance of the SOA-based extender further proves that distributed pre-amplification at the ONUs can be successfully consolidated, resulting in minimalistic and highly cost-efficient receivers at the tail-end units of fixed-access networks.