Polarization diversity scheme for reach extension of WDM/TDM gigabit passive optical network up to 60 km using quantum dot semiconductor optical amplifiers

Gigabit passive optical networks (GPON) are the most advanced technology. The data transfer rate is 2.5 Gbps for downstream and 1.25 Gbps for upstreams. But this network architecture has a limited physical network length of 20 km. This is due to the high budgetary losses of the network. This restriction of access makes the network difficult to access for subscribers located far from the facilities of the telecom operator, and coverage of remote settlements is quite costly (cost of design work, fiber, laying of fiber-optic cable), thereby complicating the elimination of the digital divide between the city, the suburbs and the countryside. To solve this problem, it is proposed to use quantum dot semiconductor optical amplifiers (QD-SOA), which will expand the GPON reach up to 60 km, which is the limit for the logical length under the current protocols. Quantum dot semiconductor optical amplifiers are promising devices for optical communication technology, but for commercial use they have one disadvantage. They are polarization sensitive. In this paper the authors constructed a polarization diversity scheme to avoid polarization sensitivity of QD-SOAs.