New concept for a regenerative amplifier for passive optical networks

Photonic balancing - a scheme where logically opposite pulses derived from the two outputs of a delay-line demodulator for phase shift keyed (PSK) signals counter-propagate in the saturated regime of a semiconductor optical amplifier (SOA) - has been proven to enhance the receiver performance, e. g. in terms of decreased optical signal-to-noise-ratio (OSNR) requirements for a given target bit error ratio (BER). Here, we extend the photonic balancing scheme towards a new concept for a regenerative amplifier targeted at extending the reach and/or the number of subscribers in passive optical networks (PON) in order to support major operators' plans to reduce the number of central offices and access areas by approximately 90%. For a given target BER, we demonstrate experimentally (a) an 8-dB higher post-amplifier loss tolerance, (b) an extended feeder line length (75 km) combined with high splitting ratio (10 layers) for a pre-amplified version, and (c) high input power variation tolerance (> 30 dB burst-to-burst) in upstream direction as needed for highly asymmetric tree structures.