Noise Performance of Bus-Configured Optical Networks with Distributed Fiber Amplification

Optical bus networks with passive taps have attracted little attention because optical- power limits severely constrain their size. It has recently been realized, however, that such constraints may be overcome using Er3+-doped fiber amplifiers. A numerical analysis [1],[2] has shown that buses with periodic amplification should be capable of supporting large numbers of nodes, even in the presence of saturating signals. Moreover, there is experimental evidence [3] that bus networks with uniformly distributed amplification generate low levels of amplified spontaneous emission (ASE). We here present a simple analysis yielding closed-form expressions showing that the amplified bus can indeed support thousands of nodes, that it can span thousands of kilometers (fiber dispersion and nonlinearity permitting), and that this excellent noise performance results from the slow growth of ASE in low-gain amplifying structures. To support large numbers of nodes, however, the bus’s gain must be well matched to its loss.