Raman-induced power tilt in arbitrarily large wavelength-division-multiplexed systems

By taking into account the finite Raman bandwidth of silica fibers, we study the so-called Raman-induced spectral power tilt in arbitrarily large wavelength-division-multiplexed systems. Our numerical results reveal that the Raman tilt reaches a maximum for a total optical bandwidth slightly larger than the Raman frequency shift and decreases beyond that, in contrast to what is predicted by the usual triangular approximation. A new analytical formulation of the Raman tilt is derived that is valid for an arbitrary number of channels and unlimited optical bandwidth. An excellent agreement is found with numerical simulations.