Recently, all-optical transport networks (AOTNs) based on wavelength division multiplexing has attracted considerabe attention to realize bit rate, format, and protocol transparent network. In this thesis, we investigate the ultimate network capacity and transparency limit of the all-optical transport networks based on node throughput.
The ultimate capacity of the AOTN is limited by ASE noise and stimulated Raman scattering (SRS). The network capacity (i.e., product of the node throughput and the transmission distance) is independent of the signal bit rate and the amplifier spacing. It increases from $1.7×10^6 (Gb/sㆍkm)$ to $3.7×10^6 (Gb/sㆍkm)$, when we increase the node throughput from 640 Gb/s to 5.12 Tb/s. The network capacity becomes independent of the bit rate and the node throughput, when we compensate SRS at each node. In this case, the network capacity is about $1.8×10^7(Gb/sㆍkm)$ which is the ultimate capacity of AOTN.
The chromatic dispersion and the self-phase modulation of the transmission fiber decrease the ultimate capacity of the network, when the transmission bit rate is higher than 10 Gb/s. On the other hand, the cross-talks induced by optical devices in optical cross-connect systems affect severely on the network with 2.5 Gb/s signal, since it requires many WDM channels to have a constant node throughput. Therefore there exists an optimum bit rate which maximizes network capacity at a given node throughput. Transparency of the network implies transmission of several bit rate signals in an AOTN. Thus it decreases the network capacity further. The capacity of the transparent network depends on the node throughput and it is about 50 ~ 80 % of the maximum network capacity optimized for a specific bit rate.
