We present a novel upstream burst-mode equalization scheme based on optimized SOA cascade for 40 Gb/s TWDMPON. The power equalizer is placed at the OLT which consists of two SOAs, two circulators, an optical NOT gate, and a variable optical attenuator. The first SOA operates in the linear region which acts as a pre-amplifier to let the second SOA operate in the saturation region. The upstream burst signals are equalized through the second SOA via nonlinear amplification. From theoretical analysis, this scheme gives sufficient dynamic range suppression up to 16.7 dB without any dynamic control or signal degradation. In addition, a total power budget extension of 9.3 dB for loud packets and 26 dB for soft packets has been achieved to allow longer transmission distance and increased splitting ratio.
Detailed numerical investigation of self-seeded colorless ONU transmitter using quantum dot (QD) SOA as the intensity modulator for symmetric 40 Gb/s TWDM-PON has been developed. It is shown that the QD SOA-based intensity modulator is able to support 10 Gb/s OOK upstream signal transmission with an optical extinction ratio of over 10 dB. Chromatic dispersion compensation free of 20 km passive transmission has been achieved for error free reception. Moreover, the system performance and power budget have been analyzed and discussed for different transmission distance and split ratio.