Effect of Channel Launch Power on Fill Margin in C+L Band Elastic Optical Networks

Increasing traffic in the optical backbone network has made it incumbent upon operators to extend the use of optical spectrum beyond the C-band. In this work we estimate network performance over the C+L band using a physical layer model for estimating the optical signal to noise ratio (OSNR) for lightpaths operating over the C+L band optical spectrum. The model considers nonlinear interference (NLI) due to inter-channel stimulated Raman scattering (ISRS) and the impact of ISRS gain on amplified spontaneous emission (ASE) noise generated by in-line amplifiers while estimating the OSNR. This model is used to account for the capacity benefits associated with OSNR estimation while considering current state of spectral occupancy to account for NLI as compared to the fully-filled, worst-case NLI assumption. OSNR estimation based on current state of spectral occupancy provide higher capacity benefits for smaller networks like the BT-UK while for larger networks like the USA NSFNET the capacity benefit is significantly reduced. Further network capacity benefits of operating over C+L band as compared to C band have been reported. For BT-UK the capacity benefit is more than 100% while for larger networks like USA NSFNET the maximum capacity benefit is 73% with 37.5 GHz of bandwidth until 10% of demands are blocked.