Impact of Fiber Attenuation and Effective Area on Spectrum Efficiency of Elastic Optical Networks

The ultra-low-loss optical fibers becoming available now offer large effective areas with much better transmission performance than conventional standard single-mode fibers (SSMFs). However, how low the attenuation should be and how large the effective area has to be to benefit the transmission performance of a fiber-optic system have been open questions until now. In the context of an elastic optical network (EON), this paper evaluates for the first time the extent to which both fiber attenuation and effective area impact the network capacity. We first present an optical signal-to-noise ratio (OSNR) model to evaluate the performance of a lightpath considering various optical transmission impairments. We also propose different service-provisioning approaches based on this OSNR model. Simulation studies show that a spectrum-dependent provisioning scheme that considers different levels of cross-channel interference (XCI) requires minimum spectrum resources when provisioning incremental demands, and a margin-reservation scheme that considers different alternate routes shows the lowest bandwidth blocking probability (BBP) when provisioning dynamic lightpath demands. We also estimate optimal launch powers needed by lightpaths for different fiber attenuations and effective areas. Under different launch powers, it is found that lowering fiber attenuation and increasing fiber effective area demonstrate saturation in performance improvement, i.e., initially decreasing fiber attenuation and increasing effective area can significantly improve the network service provisioning performance, but the improvement is much less when the fiber attenuation and effective area are lower than 0.165 dB/km and greater than 110 μm
²
, respectively. This implies that it is not necessary to fabricate a fiber with extremely low attenuation and large effective area for the best cost-to-performance ratio.