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.