Symmetrical 25-Gb/s TDM-PON With 31.5-dB Optical Power Budget Using Only Off-the-Shelf 10-Gb/s Optical Components

Increasing the serial bitrate beyond 10 Gb/s in time division multiplexed passive optical network (TDM-PON) is difficult. The reduced chromatic dispersion tolerance and the reduced signal-to-noise ratio's at higher rates make it much more challenging to achieve the needed optical power budget, especially in a cost-effective way. To combat these challenges, we investigated and demonstrated a 25-Gb/s TDM-PON, with optical amplification at the optical line termination (OLT), based on PAM-4 modulation in the downstream and Duobinary modulation in the upstream. Described in this paper is a first demonstration of a symmetrical 25-Gb/s TDM-PON with 31.5-dB class N2 power budget over 0-20 km at 1556 nm using only cost-effective off-the-shelf 10-Gb/s optical components at the ONU and OLT side. We used small form factor erbium doped fiber amplifiers as booster and preamplifier at the OLT. We also applied low-cost dispersion compensating schemes to increase chromatic dispersion tolerance, a simple predistortion scheme based on optimization of electroabsorption modulated laser bias voltage and a simple fiber dispersion supported transmission scheme. We obtained a power budget of 31.5 dB with 0-20 km of standard single mode fiber, which we doubled to 0-40 km using dispersion compensating fiber at 1556 nm (BER = 10
^-3
).