Introducing the Perturbative Solution of the Inter-Channel Stimulated Raman Scattering in Single-Mode Optical Fibers

The continuously increasing IP data traffic demand, with geometrical growth rate exceeding 26%, requires a large transmission capacity increment from the fiber optical infrastructure. As the deploy of new fiber cables requires extensive investments, the development of multi-band amplifiers and transceivers, already available as prototypes, is progressively considered towards the entire low-loss single-mode bandwidth beyond the 5 THz C-band. In this perspective, an adequate handling of the variations along the frequency of the fiber physical features becomes crucial for the fiber propagation modeling in multi-band wavelength division multiplexing (WDM) channel comb transmission scenarios. In particular, the inter-channel stimulated Raman scattering (SRS) is the fundamental inter-band effect in this context. The SRS effect on the WDM comb propagated through a single-mode optical fiber is described by a set of ordinary differential equations (ODEs). To date, an exact solution of the SRS ODEs has not been proposed, and in the literature numerical solutions or approximations have been considered in order to take into account this effect. In this work, a perturbative solution of the SRS ODEs is presented enabling an efficient trade-off between the target accuracy and the computational time. Considering a C+L+S transmission scenario, the perturbative expansion up to the 2nd order ensures an excellent accuracy. Whereas, in an U-to-E transmission scenario, the 3rd order is required in order to reach an equivalent accuracy.