Recently, there have been substantial efforts to analyze the crosstalk and estimate the networks scalability. This is because the crosstalk is one of the most significant impairments for the scalability of WDM networks. However, to our knowledge, the crosstalk has not been analyzed explicitly in terms of numbers of nodes, fibers, and wavelengths for the network‘s scalability.
In this thesis, we report a simple analytical model to estimate the scalability of WDM networks. We considered both amplified spontaneous emission(ASE) noise and homodyne crosstalk using a closed form equation. These results were used to compare the performance of various optical cross-connects(OXC‘s). The OXC based on the optical space switches and multiplexers/demultiplexers offers the best scalability.
In addition to the ASE noise and homodyne crosstalk, the passband narrowing effect of filters, fiber nonlinearities, and fiber dispersion could limit the scalability of WDM network. To evaluate the effects of these various impairments on the networks scalability, we calculated the passband narrowing effect to estimate the maximum number of concatenated filters and analyzed the fiber nonlinearities using the analytical methods. In case of using conventional single mode fiber, either self-phase modulation(SPM) or stimulated Raman scattering(SRS) was the dominant nonlinearities that limit the networks scalability.
The scalability of all optical network using OXC‘s based on the optical space switches could be limited by either SRS or passband narrowing effect of concatenated filters depending on the number of WDM channels. In case the SRS was compensated by using equalizers, the accumulation of ASE noise could limit the networks scalability. When the all optical network is implemented by using other types of OXC’s, the networks scalability was limited mostly by the ASE noise and crosstalk. This was because the ASE noise and crosstalk were increased by the couplers used in OXC's.